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1

Low thrust transfer optimisation of satellites formations to heliocentric Earth trailing orbits through a gradient restoration algorithm  

NASA Astrophysics Data System (ADS)

When dealing with mission requirements calling for highly stable gravitational and thermal environments, one of the common options always considered is that of the heliocentric Earth trailing orbits (HETO). This is the case, for instance, of the Laser Interferometer Space Antenna (LISA), a joint ESA-NASA effort aimed at detecting gravitational radiation from deep-space sources, hence testing the fundamental gravitational theories. This article is about the low-thrust transfer trajectory optimisation for a three-satellites flotilla to a HETO. To this end, and after a brief presentation of the selected reference mission (LISA), a five impulses transfer strategy is conceived to build a solution guess for the ignition of the Sequential Gradient Restoration Algorithm (SGRA), which solves the full optimal control problem (FOCP) of finding the optimal low thrust profiles injecting each SC to its respective target orbit while minimising a given functional. An inequality path constraint on the Solar Aspect Angle (SAA) is imposed on the low-thrust vector of each SC. Finally several relevant conclusions are derived from the presented results, among them the direct relationship between the departure velocity from Earth, the final SC masses and the transfer duration.

Bastante, J. C.; Caramagno, A.; Peñín, L. F.; Belló-Mora, M.; Rodríguez-Canabal, J.

2004-08-01

2

Lifetimes of small bodies in planetocentric (or heliocentric) orbits  

NASA Astrophysics Data System (ADS)

Stray bodies orbiting a planet or the Sun are removed by collisions with larger objects or by expulsion from the system. However, their rate of removal generally cannot be described by the simple exponential law used to describe radioactive decay, because their effective half-life lengthens with time. Previous studies of planetesimals, comets, asteroids, meteorites, and impact ejecta from planets or satellites have fit the number of survivors S vs elapsed time t using exponential, logarithmic, and power laws, but no entirely satisfactory functional form has been found yet. Herein we model the removal rates of impact ejecta from various moons of Jupiter, Saturn, and Neptune. We find that most situations are fit best by stretched exponential decay, of the form S(t)=S(0)exp(-[). Here t is the time when the initial population has declined by a factor of e?2.72, while the dimensionless exponent ? lies between 0 and 1 (often near 1/3). The e-folding time S[ itself grows as the [1-?] power of t. This behavior is suggestive of a diffusion-like process.

Dobrovolskis, Anthony R.; Alvarellos, José L.; Lissauer, Jack J.

2007-06-01

3

Temporary Capture of Planetesimals by a Planet from Their Heliocentric Orbits  

NASA Astrophysics Data System (ADS)

When planetesimals encounter a planet, they can be temporarily captured by the planet's gravity and orbit about it for an extended period of time before escaping from the planet's vicinity. Such a process may have played an important role in the origin of irregular satellites or the dynamical evolution of short-period comets. Using three-body orbital integration, we study the temporary capture of planetesimals by a planet from their heliocentric eccentric orbits. We examine the dependence of the orbital characteristics during temporary capture as well as the rate of capture on the pre-capture heliocentric orbital parameters. We find that typical orbital size and direction of revolution around the planet change depending on planetesimals' initial eccentricity and energy. When initial eccentricity is so small that Kepler shear dominates the relative velocity between planetesimals and the planet, temporary capture typically occurs in the retrograde direction in the vicinity of the planet's Hill sphere, while large retrograde capture orbits outside the Hill sphere are predominant for large eccentricities. Long prograde capture occurs in a very narrow range of planetesimal eccentricity and energy. We obtain the rate of temporary capture of planetesimals and find that the rate of long capture increases with increasing eccentricity at low and high eccentricities, but decreases with increasing eccentricity in intermediate values of eccentricity. We also examine the dependence of capture rate on the duration of capture and find an approximate power-law dependence.

Suetsugu, Ryo; Ohtsuki, Keiji; Tanigawa, Takayuki

2011-12-01

4

TEMPORARY CAPTURE OF PLANETESIMALS BY A PLANET FROM THEIR HELIOCENTRIC ORBITS  

SciTech Connect

When planetesimals encounter a planet, they can be temporarily captured by the planet's gravity and orbit about it for an extended period of time before escaping from the planet's vicinity. Such a process may have played an important role in the origin of irregular satellites or the dynamical evolution of short-period comets. Using three-body orbital integration, we study the temporary capture of planetesimals by a planet from their heliocentric eccentric orbits. We examine the dependence of the orbital characteristics during temporary capture as well as the rate of capture on the pre-capture heliocentric orbital parameters. We find that typical orbital size and direction of revolution around the planet change depending on planetesimals' initial eccentricity and energy. When initial eccentricity is so small that Kepler shear dominates the relative velocity between planetesimals and the planet, temporary capture typically occurs in the retrograde direction in the vicinity of the planet's Hill sphere, while large retrograde capture orbits outside the Hill sphere are predominant for large eccentricities. Long prograde capture occurs in a very narrow range of planetesimal eccentricity and energy. We obtain the rate of temporary capture of planetesimals and find that the rate of long capture increases with increasing eccentricity at low and high eccentricities, but decreases with increasing eccentricity in intermediate values of eccentricity. We also examine the dependence of capture rate on the duration of capture and find an approximate power-law dependence.

Suetsugu, Ryo; Ohtsuki, Keiji [Department of Earth and Planetary Sciences, Kobe University, Kobe 657-8501 (Japan); Tanigawa, Takayuki, E-mail: ryo3088@stu.kobe-u.ac.jp [Center for Planetary Science, Kobe University, Kobe 650-0047 (Japan)

2011-12-15

5

Simulations of the Solar Orbiter spacecraft interactions with the Solar wind at different heliocentric distances: effects on SWA-EAS measurements  

NASA Astrophysics Data System (ADS)

This presentation focuses on numerical simulations of the Solar Orbiter spacecraft/plasma interactions performed with the Spacecraft Plasma Interaction System (SPIS) software (http://dev.spis.org/projects/spine/home/spis/). This toolkit aims at modelling spacecraft-plasma interactions, based on an electrostatic 3-D unstructured particle-in-cell plasma model. New powerful SPIS functionalities were recently delivered within the extension of the software: SPIS-Science (ESA contract). This version revolutionizes spacecraft/plasma interactions as users are now able to model and configure plasma instrument such as Langmuir probes or particle detectors taking into account instrument characteristics like geometry, materials, energy ranges and resolution, output frequency, field of view ... In the validation context of SPIS-Science functionalities, a simulation campaign was carried out, including several cases of the ESA Solar Orbiter mission. The results presented here specifically focus on particle measurements through the modelling of the Solar Wind Analyzer - Electron Analyzer System instrument (SWA-EAS). Simulations of the spacecraft in different environments have been performed and extensively analysed. A detailed analysis will be presented concerning 1/ the satellite charging and, in particular, differential potentials on the dielectric surfaces of the Solar panels and the High Gain Antenna, which may severely affect low energy EAS measurements, 2/ the surrounding plasma behaviour : potential barriers for secondary and photoelectrons of about -5 V around the vehicle are indeed observed at the mission perihelion of 0.28 AU from the Sun and 3/ a quantification of biases on EAS measurements due to the combined effects of surface potentials, ion wake, and potential barriers. This work proposes a general framework to prepare the analysis of the future Solar Orbiter measurements.

Guillemant, S.; Genot, V. N.; Matéo Vélez, J.; Sarrailh, P.; Louarn, P.; Maksimovic, M.; Owen, C. J.; Hilgers, A. M.

2013-12-01

6

Models of angular momentum input to a circum-terrestrial swarm from encounters with heliocentric planetesimals  

NASA Technical Reports Server (NTRS)

Models of lunar origin in which the Moon accretes in orbit about the Earth from material approaching the Earth from heliocentric orbits must overcome a fundamental problem: the approach orbits of such material would be, in the simplest approximation, equally likely to be prograde or retrograde about the Earth, with the result that accretion of such material adds mass but not angular momentum to circumterrestrial satellites. Satellite orbits would then decay due to the resulting drag, ultimately impacting onto the Earth. One possibility for adding both material and angular momentum to Earth orbit is investigated: imbalance in the delivered angular momentum between pro and retrograde Earth passing orbits which arises from the three body dynamics of planetesimals approaching the Earth from heliocentric space. In order to study angular momentum delivery to circumterrestrial satellites, the near Earth velocities were numerically computed as a function of distance from the Earth for a large array of orbits systematically spanning heliocentric phase space.

Davis, D. R.; Greenberg, R.; Hebert, F.

1985-01-01

7

Ancient Greek Heliocentric Views Hidden from Prevailing Beliefs?  

NASA Astrophysics Data System (ADS)

We put forward the working hypothesis that the heliocentric, rather than the geocentric view, of the Solar System was the essential belief of the early Greek philosophers and astronomers. Although most of them referred to the geocentric view, it is plausible that the prevalent religious beliefs about the sacred character of the Earth as well as the fear of prosecution for impiety (asebeia) prevented them from expressing the heliocentric view, even though they were fully aware of it. Moreover, putting the geocentric view forward, instead, would have facilitated the reception of the surrounding world and the understanding of everyday celestial phenomena, much like the modern presentation of the celestial sphere and the zodiac, where the Earth is at the centre and the Sun makes an apparent orbit on the ecliptic. Such an ingenious stance would have set these early astronomers in harmony with the dominant religious beliefs and, at the same time, would have helped them to 'save the appearances', without sacrificing the essence of their ideas. In Hellenistic and Roman times, the prevailing view was still the geocentric one. The brilliant heliocentric theory advanced by Aristarchos in the early third century B.C. was never established, because it met with hostility in Athens - Aristarchos was accused of impiety and faced the death penalty. The textual evidence suggests that the tight connection which existed between religion and the city-state (polis) in ancient Greece, and which led to a series of impiety trials against philosophers in Athens during the fifth and fourth centuries B.C., would have made any contrary opinion expressed by the astronomers seem almost a high treason against the state.

Liritzis, Ioannis; Coucouzeli, Alexandra

2008-03-01

8

Heliocentric zoning of the asteroid belt by aluminum-26 heating  

NASA Technical Reports Server (NTRS)

Variations in petrology among meteorites attest to a strong heating event early in solar system history, but the heat source has remained unresolved. Aluminum-26 has been considered the most likely high-energy, short-lived radionuclide (half-life 0.72 million years) since the discovery of its decay product - excess Mg-26 - in Allende CAI's. Furthermore, observation of relict Mg-26 in an achondritic clast and in feldspars within ordinary chondrites (3,4) provided strong evidence for live Al-26 in meteorite parent bodies and not just in refractory nebular condensates. The inferred amount of Al-26 is consistent with constraints on the thermal evolution of both ordinary and carbonaceous chondrite parent objects up to a few hundred kilometers in diameter. Meteorites can constrain the early thermal evolution of their parent body locations, provided that a link can be established between asteroid spectrophotometric signature and meteorite class. Asteroid compositions are heliocentrically distributed: objects thought to have experienced high metamorphic or even melting temperatures are located closer to the sun, whereas apparently unaltered or mildly heated asteroids are located farther away. Heliocentric zoning could be the result of Al-26 heating if the initial amount of the radionuclide incorporated into planetesimals was controlled by accretion time, which in turn varies with semimajor axis. Analytic expressions for planetary accretion may be integrated to given the time, tau, required for a planetesimal to grow to a specified radius: tau varies as a(sup n), where n = 1.5 to 3 depending on the assumptions about variations in the surface density of the planetesimal swarm. Numerical simulations of planetesimal accretion at fixed semimajor axis demonstrate that variations in accretion time among small planetesimals can be strongly nonlinear depending on the initial conditions and model assumptions. The general relationship with semimajor axis remains valid because it depends only on the initial orbit properties and distribution of the planesimal swarm. In order to demonstrate the basic dependence of thermal evolution on semimajor axis, we parameterized accretion time across the asteroid belt according to tau varies as a(sup n) and calculated the subsequent thermal history. Objects at a specified semimajor axis were assumed to have the same accretion time, regardless of size. We set the initial Al-26/Al-27 ratio = 6 x 10(exp -5) and treated n and tau(sub 0) at a(sub 0) = 3 AU as adjustable parameters. The thermal model included temperature-dependent properties of ice and rock (CM chondrite analog) and the thermodynamic effects of phase transitions.

Grimm, R. E.; Mcsween, H. Y., Jr.

1993-01-01

9

CCD-Photometry of Comets at Large Heliocentric Distances.  

National Technical Information Service (NTIS)

CCD imaging and time series photometry are used to determine the state of activity, nuclear properties and eventually the rotational motion of cometary nuclei. Cometary activity at large heliocentric distances and mantle evolution are not yet fully unders...

B. E. A. Mueller

1992-01-01

10

Proof-of-Concept Trajectory Designs for a Multi-Spacecraft, Low-Thrust Heliocentric Solar Weather Buoy Mission  

NASA Technical Reports Server (NTRS)

A new solar weather mission has been proposed, involving a dozen or more small spacecraft spaced at regular, constant intervals in a mutual heliocentric circular orbit between the orbits of Earth and Venus. These solar weather buoys (SWBs) would carry instrumentation to detect and measure the material in solar flares, solar energetic particle events, and coronal mass ejections as they flowed past the buoys, serving both as science probes and as a radiation early warning system for the Earth and interplanetary travelers to Mars. The baseline concept involves placing a mothercraft carrying the SWBs into a staging orbit at the Sun-Earth L1 libration point. The mothercraft departs the L1 orbit at the proper time to execute a trailing-edge lunar flyby near New Moon, injecting it into a heliocentric orbit with its perihelion interior to Earth s orbit. An alternative approach would involve the use of a Double Lunar Swingby (DLS) orbit, rather than the L1 orbit, for staging prior to this flyby. After injection into heliocentric orbit, the mothercraft releases the SWBs-all equipped with low-thrust pulsed plasma thrusters (PPTs)-whereupon each SWB executes a multi-day low-thrust finite bum around perihelion, lowering aphelion such that each achieves an elliptical phasing orbit of different orbital period from its companions. The resulting differences in angular rates of motion cause the spacecraft to separate. While the lead SWB achieves the mission orbit following an insertion burn at its second perihelion passage, the remaining SWBs must complete several revolutions in their respective phasing orbits to establish them in the mission orbit with the desired longitudinal spacing. The complete configuration for a 14 SWB scenario using a single mothercraft is achieved in about 8 years, and the spacing remains stable for at least a further 6 years. Flight operations can be simplified, and mission risk reduced, by employing two mothercraft instead of one. In this scenario: the second mothercraft stays in a libration-point or DLS staging orbit until the first mothercraft has achieved nearly 180 separation from the Earth. The timing of the second mothercraft's subsequent lunar flyby is planned such that this spacecraft will be located 180 from the first mothercraft upon completion of its heliocentric circularization maneuvers. Both groups of satellites then only have to spread out over 180 to obtain full 360 coverage around the Sun.

Muller, Ronald; Franz, Heather; Roberts, Craig; Folta, Dave

2005-01-01

11

LISA Orbits  

Microsoft Academic Search

The LISA formation is composed of 3 spacecraft in an equilateral triangle formation. The baseline formation has a 5million km radius and lies in a heliocentric orbit 20deg away from the Earth. Earth's gravity induces a perturbation on the nominal Keplerian motion of the formation, generating a change in the relative ranges and thus a Doppler that can be very

Angelo Povoleri; Stephen Kemble

2006-01-01

12

67P/Churyumov-Gerasimenko: start of activity and heliocentric light curve  

NASA Astrophysics Data System (ADS)

Comets are believed to be widely unmodified remnants from the formation of the solar system; their study can give important insights into the conditions prevailing at the time of the planetary system formation. After the success of the Giotto mission to comet 1P/Halley, the European Space Agency (ESA) approved in the early nineties a new space mission with a comet as main target: Rosetta, which will rendezvous with come 67P/Churyumov-Gerasimenko (67P/C-G) in 2014. 67P/C-G is a Jupiter family comet with orbital period of 6.56 years. Due to repeated encounters with Jupiter, the orbital evolution of 67P/C-G is chaotic. The last encounter in February 1959 occurred at a distance of only 0.0518 AU and produced drastic changes in perihelion distance, eccentricity, inclination, orbital period and possibly led to its discovery in 1969. After 67P/C-G was selected as target comet of Rosetta mission, observational campaigns and theoretical investigations were performed in order to establish a detailed portrait of 67P/C-G in preparation of the rendezvous with the spacecraft ([1], [2], [3], [4]). Here we present ground-based observations of 67P/CG obtained between July 2007 and March 2008 at ESO VLT using the FORS2 instrument. The comet was moving inbound, from 4.6 AU to 3.4 AU. The orbital arc covered by our observation is the same where 67P/C-G will be in 2014 when the rendezvous with the Rosetta spacecraft will take place, thus of highly interest for mission planning. Since the comet's activity around perihelion has shown similar behaviour during the last three orbital passages, it is fair to assume that the comet's behavior at large heliocentric distance has not changed from one orbital revolution to the other, leading us to expect that during its approach to 67P/CG, Rosetta will find the same conditions detected during our observations. A considerable difficulty in observing 67P/C-G during the past years has been its position against crowded fields towards the galactic centre for much of this time (Fig. 1 - top). The 2007/8 data presented here was particularly difficult, and the comet will once again be badly placed for Earth based observations in 2014/5. We made use of the technique of Difference Image Analysis (as implemented in the DanDIA software, [5]), which is commonly used in variable star and exoplanet research, to remove background sources and extract images of the comet (Fig. 1 - bottom). We determined that the comet became active during the period November 2007 - March 2008, at a distance of 4.1-3.4 AU from the Sun. The comet will reach this distance, and probably become active again, in April- September 2014. To investigate the longer period activity cycle of the comet we compiled the heliocentric light curve of the comet, making use of images of 67P/C-G taken during the last three apparitions taken from the ESO archive. A preliminary light curve is shown in 2. This information will be used for planning observing campaigns, both from the ground and using OSIRIS on board Rosetta.

Tubiana, C.; Snodgrass, C.; Bramich, D.; Boehnhardt, H.; Barrera, L.

2012-09-01

13

No evidence for a decrease of nuclear decay rates with increasing heliocentric distance based on radiochronology of meteorites  

NASA Astrophysics Data System (ADS)

It has been argued that the decay rates of several radioactive nuclides are slightly lower at Earth's aphelion than at perihelion, and that this effect might depend on heliocentric distance. It might then be expected that nuclear decay rates be considerably lower at larger distances from the sun, e.g., in the asteroid belt at 2-3 AU from where most meteorites originate. If so, ages of meteorites obtained by analyses of radioactive nuclides and their stable daughter isotopes might be in error, since these ages are based on decay rates determined on Earth. Here we evaluate whether the large data base on nuclear cosmochronology offers any hint for discrepancies which might be due to radially variable decay rates. Chlorine-36 (t1/2 = 301,000 a) is produced in meteorites by interactions with cosmic rays and is the nuclide for which a decay rate dependence from heliocentric distance has been proposed, which, in principle, can be tested with our approach and the current data base. We show that compilations of 36Cl concentrations measured in meteorites offer no support for a spatially variable 36Cl decay rate. For very short-lived cosmic-ray produced radionuclides (half-lives < 10-100 days), the concentration should be different for meteorites hitting the Earth on the incoming vs. outgoing part of their orbit. However, the current data base of very short-lived radionuclides in freshly fallen meteorites is far from sufficient to deduce solid constraints. Constraints on the age of the Earth and the oldest meteorite phases obtained by the U-Pb dating technique give no hints for radially variable decay rates of the ?-decaying nuclides 235U or 238U. Similarly, some of the oldest phases in meteorites have U-Pb ages whose differences agree almost perfectly with respective age differences obtained with "short-lived" radionuclides present in the early solar system, again indicating no variability of uranium decay rates in different meteorite parent bodies in the asteroid belt. Moreover, the oldest U-Pb ages of meteorites agree with the main-sequence age of the sun derived from helioseismology within the formal ˜1% uncertainty of the latter. Meteorite ages also provide no evidence for a decrease of decay rates with heliocentric distance for nuclides such as 87Rb (decay mode ?-) 40K (?- and electron capture), and 147Sm (?).

Meier, Matthias M. M.; Wieler, Rainer

2014-03-01

14

The trend of production rates with heliocentric distance for comet P/Halley  

NASA Technical Reports Server (NTRS)

Comet P/Halley was observed spectroscopically in the wavelength range 5200-10,400 A during 10 observing runs, roughly a month apart from 1985 August 28 to 1986 June 6. The observations span a heliocentric distance from 0.73 to 2.52 AU. This data set is analyzed to determine the course of the production rate with heliocentric distance for C2, NH2, CN, and the continuum. The effect of changing the Haser scale lengths and their heliocentric distance dependence is examined. The production rate ratios to water change only in a minor way, but the absolute values of the production rates are more severely affected. Fluorescent efficiencies, or g-factors for the CN red system are calculated, and band intensity ratios for NH2 and CN are presented. Using presently available fluorescence efficiencies and Haser scale lengths, mixing ratios for the parents of C2, CN, and NH2 with respect to water are: 0.34 +/- 0.07%, 0.15 +/- 0.04%, and 0.13 +/- 0.05%. It is found that these mixing ratios are essentially constant over the heliocentric distance range of the observations, implying a rather uniform nucleus and uniform outgassing characteristics, although there are indications of smaller scale day-to-day variations. The results provide strong observational confirmation that water evaporation controls the activity of the comet over the distance range studied. Continuum values Af rho are determined, and their ratios to QH2O are found to have a clear dependence with heliocentric distance approximately r(exp -1.0) with a post-perihelion enhancement. No correlation of the production rate ratios with light curve of P/Halley were found, nor was there any correlation of the C2 or CN production with the dust.

Fink, Uwe

1994-01-01

15

Orbits about the sun intended for radiosonde observations of the solar space  

Microsoft Academic Search

The problem of obtaining an orbit about the sun whose orbital elements coincide with the elements of the earth's orbit is examined. The perihelion argument of the former differs from that of the latter by 180 degrees. If the probe is placed into a heliocentric orbit that is symmetrical to the earth, then the earth, sun and probe will be

G. A. Mersov

1976-01-01

16

Dust emission from comets at large heliocentric distances. I - The case of comet Bowell /1980b/  

NASA Technical Reports Server (NTRS)

Alternative processes of dust emission from comets at large heliocentric distances are considered, in order to explain the dust coma observed in comet Bowell (1980b) at a heliocentric distance as large as 7.17 AU. It is shown that the electrostatic blow-off of dust from a charged, H2O-dominated nucleus having a layer of loose, fine dust may be the formation process of the dust coma, with the coma size expected from the process being comparable to the observed value and the dust grain size being equal to or less than 0.4 microns in size. The upper limit for the total mass in the coma is 3.9 x 10 to the 8th g, and the spatial extension less than 10,000 km. The observed activity may alternatively be due to dust entrainment by the sublimating gas from a CO2-dominated nucleus.

Houpis, H. L. F.; Mendis, D. A.

1981-01-01

17

On the Provability of Heliocentrism. II. Leon Foucault and the Rotation of the Earth  

NASA Astrophysics Data System (ADS)

This paper deals with the experimental provability of heliocentrism from the scientific Renaissance in the beginning of the 17th century, till the Industrial Revolution of the 1850s. Foucault's famous pendulum demonstration is documented. We underline the importance of high accuracy of observations, the interdependence of hypotheses and theories, the impact of technological breakthroughs, the role of serendipity, the importance of fast and accurate publishing, and the need for precise science communication and teaching.

Sterken, Christiaan

2007-10-01

18

Pioneer 10 observations of zodiacal light brightness near the ecliptic - Changes with heliocentric distance  

NASA Technical Reports Server (NTRS)

Sky maps made by the Pioneer 10 Imaging Photopolarimeter (IPP) at sun-spacecraft distances from 1 to 3 AU have been analyzed to derive the brightness of the zodiacal light near the ecliptic at elongations greater than 90 degrees. The change in zodiacal light brightness with heliocentric distance is compared with models of the spatial distribution of the dust. Use of background starlight brightnesses derived from IPP measurements beyond the asteroid belt, where the zodiacal light is not detected, and, especially, use of a corrected calibration lead to considerably lower values for zodiacal light than those reported by us previously.

Hanner, M. S.; Weinberg, J. L.; Beeson, D. E.; Sparrow, J. G.

1976-01-01

19

Sublimation rates of carbon monoxide and carbon dioxide from comets at large heliocentric distances  

NASA Technical Reports Server (NTRS)

Using a simple model for outgassing from a small flat surface area, the sublimation rates of carbon monoxide and carbon dioxide, two species more volatile than water ice that are known to be present in comets, are calculated for a suddenly activated discrete source on the rotating nucleus. The instantaneous sublimation rate depends upon the comet's heliocentric distance and the Sun's zenith angle at the location of the source. The values are derived for the constants of CO and CO2 in an expression that yields the local rotation-averaged sublimation rate as a function of the comet's spin parameters and the source's cometocentric latitude.

Sekanina, Zdenek

1992-01-01

20

Science-philosophy relation and the prevalence of the heliocentric theory.  

NASA Astrophysics Data System (ADS)

The relation between philosophy and science has passed from many phases in history and still is an interesting topic. The value of falsifiability (or refutability) in science was stressed by Popper. Here, as a paradigm, the juxtaposition of the Earth-centered view of the universe and the prevalence of the heliocentric theory is examined. A new physics appeared in the West in the 17th century, under the Cartesian philosophical canopy, the spirit of which had its deep influence on the savants of that period. This new physics, as defined by Galileo and Kepler, was not searching for purpose, but it was seeking for causes.

Theodossiou, E.; Manimanis, V. N.; Danezis, E.

21

The spectrum and spatial distribution of cyanogen in comet Hale-Bopp (C/1995 O1) at large heliocentric distance.  

PubMed

Optical spectra of comet Hale-Bopp (C/1995 O1) at a heliocentric distance of 6.45 astronomical units showed emission from cyanogen gas. The spatial distribution of cyanogen was considerably more diffuse and extended compared to the spatial profile of the dust or grains which were sharply peaked near the center. This behavior is consistent with comets at smaller heliocentric distances suggesting the same or a similar formation mechanism. A cyanogen gas production rate of (1.2 +/- 0.3) x10(26) molecules per second was derived. A model band profile derived from fluorescence equilibrium calculations for the comet's heliocentric velocity and distance agrees with the observed band profile. PMID:9072965

Wagner, R M; Schleicher, D G

1997-03-28

22

Optical observations of comet Hale-Bopp (C/1995 O1) at large heliocentric distances before perihelion.  

PubMed

The activity of comet Hale-Bopp (C/1995 O1) was monitored monthly by optical imaging and long-slit spectroscopy of its dust and gas distribution over heliocentric distances of 4.6 to 2.9 astronomical units. The observed band intensities of the NH2 radical and the H2O+ ion cannot be explained by existing models of fluorescence excitation, warranting a reexamination of the corresponding production rates, at least at large heliocentric distances. Comparing the production rate of the CN radical to its proposed parent, HCN, shows no evidence for the need of a major additional source for CN in Hale-Bopp at large heliocentric distances. The dust and CN production rates are consistent with a significant amount of sublimation occurring from icy dust grains surrounding Hale-Bopp. PMID:9072962

Rauer, H; Arpigny, C; Boehnhardt, H; Colas, F; Crovisier, J; Jorda, L; Küppers, M; Manfroid, J; Rembor, K; Thomas, N

1997-03-28

23

Spitzer Orbit Determination During In-orbit Checkout Phase  

NASA Technical Reports Server (NTRS)

The Spitzer Space Telescope was injected into heliocentric orbit on August 25, 2003 to observe and study astrophysical phenomena in the infrared range of frequencies. The initial 60 days was dedicated to Spitzer's "In-Orbit Checkout (IOC)" efforts. During this time high levels of Helium venting were used to cool down the telescope. Attitude control was done using reaction wheels, which in turn were de-saturated using cold gas Nitrogen thrusting. Dense tracking data (nearly continuous) by the Deep Space network (DSN) were used to perform orbit determination and to assess any possible venting imbalance. Only Doppler data were available for navigation. This paper deals with navigation efforts during the IOC phase. It includes Dust Cover Ejection (DCE) monitoring, orbit determination strategy validation and results and assessment of non-gravitational accelerations acting on Spitzer including that due to possible imbalance in Helium venting.

Menon, Premkumar R.

2004-01-01

24

Telemetry coding study for the international magnetosphere explorers, mother/daughter and heliocentric missions. Volume 2: Final report  

NASA Technical Reports Server (NTRS)

A convolutional coding theory is given for the IME and the Heliocentric spacecraft. The amount of coding gain needed by the mission is determined. Recommendations are given for an encoder/decoder system to provide the gain along with an evaluation of the impact of the system on the space network in terms of costs and complexity.

Cartier, D. E.

1973-01-01

25

Substantial outgassing of CO from comet Hale-Bopp at large heliocentric distance.  

PubMed

When comet C/1995 O1 (Hale-Boop) was discovered, at a distance of seven astronomical units from the sun, it was more than one hundred times brighter than comet Halley at the same distance. A comet's brightness is derived from the reflection of sunlight from dust grains driven away from the nucleus by the sublimation of volatile ices. Near the sun, sublimation of water ice (a main constituent of comet nuclei) is the source of cometary activity; but at its current heliocentric distance, Hale-Boop is too cold for this process to operate. Other comets have shown activity at large distances, and in the case of comet Schwassmann-Wachmann 1, carbon monoxide has been detected in quantities sufficient to generate its observed coma. Here we report the detection of CO emission from Hale-Boop, at levels indicating a very large rate of outgassing. Several other volatile species were searched for, but not detected. Sublimation of CO therefore appears to be responsible for the present activity of this comet, and we anticipate that future observations will reveal the onset of sublimation of other volatile species as the comet continues its present journey towards the sun. PMID:8600385

Biver, N; Rauer, H; Despois, D; Moreno, R; Paubert, G; Bockelée-Morvan, D; Colom, P; Crovisier, J; Gérard, E; Jorda, L

1996-03-14

26

EVOLUTION OF CORONAL MASS EJECTION MORPHOLOGY WITH INCREASING HELIOCENTRIC DISTANCE. I. GEOMETRICAL ANALYSIS  

SciTech Connect

At launch, coronal mass ejections (CMEs) are often approximated as locally cylindrical objects with circular cross sections. However, CMEs have long been known to propagate almost radially away from the Sun along with the bulk solar wind. This has important consequences for the structure of CMEs; an initially circular cross section will be severely flattened by this radial motion. Yet calculations of total flux and helicity transport by CMEs based on in situ observations still use the assumption of a locally cylindrical object. In this paper, we investigate the morphology of an interplanetary CME based upon geometric arguments. By radially propagating an initial cylindrical object that maintains a constant ratio between its expansion speed and bulk flow, A, we show that the flattening, or 'pancaking', of the two-dimensional cross section effectively ceases; the aspect ratios of these CMEs converge to a fixed value as they propagate further into the heliosphere. Thereafter the CME morphology is scale invariant. We predict aspect ratios of 5 {+-} 1 at terrestrial distances. By correlating a planetary shock with an interplanetary shock linked to a CME, these aspect ratios are estimated using in situ measurements in Paper II. These estimates are made at various heliocentric distances.

Savani, N. P.; Kusano, K. [Solar-Terrestrial Environment Laboratory, Nagoya University, Nagoya 464-8601 (Japan); Owens, M. J. [Space Environment Physic Group, University of Reading, Earley Gate, P.O. Box 243, Reading RG6 6BB (United Kingdom); Rouillard, A. P. [College of Science, George Mason University, Fairfax, VA 22030 (United States); Forsyth, R. J. [Blackett Laboratory, Imperial College London, Prince Consort Road London SW7 2BZ (United Kingdom); Shiota, D. [Computational Astrophysics Laboratory, Advanced Science Institute, RIKEN, 2-1, Hirosawa, Wako, Saitama 351-0198 (Japan); Kataoka, R., E-mail: neel.savani02@imperial.ac.uk [Interactive Research Center of Science, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro, Tokyo 152-8551 (Japan)

2011-04-20

27

Study of the Forbidden Oxygen Lines in Comets at Different Heliocentric and Nucleocentric Distances  

NASA Astrophysics Data System (ADS)

Oxygen is an important element in the chemistry of the solar system objects given its abundance and its presence in many molecules including H2O 80% of cometary ices). The analysis of oxygen atoms in comets can provide information not only on the comets themselves but also on the solar system. These atoms have been analyzed using the 3 forbidden oxygen lines [OI] observed in emission in the optical region at 5577.339 Å (the green line), 6300.304 Å and 6363.776 Å (the red lines) (Swings, 1962). Our analysis is based on a sample of 12 comets of various origins. The observing material is made of 53 high signal-to-noise spectra obtained with the high-resolution UVES spectrograph at the ESO VLT from 2002 to 2012 (Manfroid et al, 2009). After noticing that the green line is blended with one C2 line, we built synthetic spectra of C2 for each observing circumstances and we subtracted its contribution to the cometary spectra in order to ensure the decontamination of the 5577 Å line. Then, we measured the intensity of the 3 [OI] lines at different heliocentric distances. By comparing the green to red lines ratio (G/R) with the Bhardwaj & Raghuram (2012) effective excitation rates, we found that H2O is the main parent molecule when the comet is observed at 1 au. When the comet is located beyond 2.5 au from the Sun, CO2 also contributes to the production of oxygen. Studying forbidden oxygen lines could be a new way to estimate the abundances of CO2 in comets, a very difficult task from the ground (Decock et al. 2013). In order to estimate the effect of the quenching on our results, we analyzed the evolution of the G/R ratio at different nucleocentric distances. For nearby comets, we divided the extended 2D spectrum into several zones in order to analyze the oxygen lines as close as possible to the nucleus (down to ~10 km for the closest comets). Their analysis will allow us to study the link of the oxygen lines with the nucleocentric distance. We found a clear variation of the G/R ratio close to the comet nucleus that is in agreement with a contribution from CO2 as predicted by Raghuram & Bhardwaj (2013).

Decock, Alice; Rousselot, P.; Jehin, E.; Hutsemékers, D.; Manfroid, J.; Bhardwaj, A.; Raghuram, S.

2013-10-01

28

Data catalog series for space science and applications flight missions. Volume 1A: Brief descriptions of planetary and heliocentric spacecraft and investigations  

NASA Technical Reports Server (NTRS)

Planetary and heliocentric spacecraft, including planetary flybys and probes, are described. Imaging, particles and fields, ultraviolet, infrared, radio science and celestial mechanics, atmospheres, surface chemistry, biology, and polarization are discussed.

Cameron, W. S. (editor); Vostreys, R. W. (editor)

1982-01-01

29

Possible Periodic Orbit Control Maneuvers for an eLISA Mission  

NASA Technical Reports Server (NTRS)

This paper investigates the possible application of periodic orbit control maneuvers for so-called evolved-LISA (eLISA) missions, i.e., missions for which the constellation arm lengths and mean distance from the Earth are substantially reduced. We find that for missions with arm lengths of 106 km and Earth-trailing distance ranging from approx. 12deg to 20deg over the science lifetime, the occasional use of the spacecraft micro-Newton thrusters for constellation configuration maintenance should be able to essentially eliminate constellation distortion caused by Earth-induced tidal forces at a cost to science time of only a few percent. With interior angle variation kept to approx. +/-0:1deg, the required changes in the angles between the laser beam pointing directions for the two arms from any spacecraft could be kept quite small. This would considerably simplify the apparatus necessary for changing the transmitted beam directions.

Bender, Peter L.; Welter, Gary L.

2012-01-01

30

Possible Periodic Orbit Control Maneuvers for an eLISA Mission  

NASA Astrophysics Data System (ADS)

This paper investigates the possible application of periodic orbit control maneuvers for so-called evolved-LISA (eLISA) missions, i.e., missions for which the constellation arm lengths and mean distance from the Earth are substantially reduced. We find that for missions with arm lengths of ˜ 106 km and Earth-trailing distance ranging from ˜ 12° to 20° over the science lifetime, the occasional use of the spacecraft micro-Newton thrusters for constellation configuration maintenance should be able to essentially eliminate constellation distortion caused by Earth-induced tidal forces at a cost to science time of only a few percent. With interior angle variation kept to ˜ ± 0.1°, the required changes in the angles between the laser beam pointing directions for the two arms from any spacecraft could be kept quite small. This would considerably simplify the apparatus necessary for changing the transmitted beam directions.

Bender, P. L.; Welter, G. L.

2013-01-01

31

New estimate of the micrometeoroids flux at the heliocentric distance of Mercury  

Microsoft Academic Search

This work shows preliminary results of a study of the orbital evolution of dust particles originating from the Main Belt in order to obtain a statistical analysis, then to provide an estimate of the flux of particles hitting the Mercury's surface. Meteoritic flux on Mercury really depends on the particle size, because meteoroids of different size follow different dynamical evolution.

Patrizia Borin; Gabriele Cremonese; Francesco Marzari

2008-01-01

32

Orbit Determination and Navigation of the Solar Terrestrial Relations Observatory (STEREO)  

NASA Technical Reports Server (NTRS)

This paper provides an overview of the required upgrades necessary for navigation of NASA's twin heliocentric science missions, Solar TErestrial RElations Observatory (STEREO) Ahead and Behind. The orbit determination of the STEREO spacecraft was provided by the NASA Goddard Space Flight Center's (GSFC) Flight Dynamics Facility (FDF) in support of the mission operations activities performed by the Johns Hopkins University Applied Physics Laboratory (APL). The changes to FDF's orbit determination software included modeling upgrades as well as modifications required to process the Deep Space Network X-band tracking data used for STEREO. Orbit results as well as comparisons to independently computed solutions are also included. The successful orbit determination support aided in maneuvering the STEREO spacecraft, launched on October 26, 2006 (00:52 Z), to target the lunar gravity assists required to place the spacecraft into their final heliocentric drift-away orbits where they are providing stereo imaging of the Sun.

Mesarch, Michael A.; Robertson, Mika; Ottenstein, Neil; Nicholson, Ann; Nicholson, Mark; Ward, Douglas T.; Cosgrove, Jennifer; German, Darla; Hendry, Stephen; Shaw, James

2007-01-01

33

Identification of satellites possibly active during the IMS and their orbital configurations. [International Magnetospheric Study  

NASA Technical Reports Server (NTRS)

A survey has been made to identify presently operating as well as planned spacecraft which may contribute measurements of the magnetosphere or interplanetary medium during the IMS. The total set consists of 25 scientific earth-orbiting, 9 heliocentric, and 17 communication, navigation or meteorological spacecraft, which carry environmental monitoring experiments. The orbital elements of each are displayed. In addition, techniques for the display of positions in various orbits are presented to illustrate how interesting configurations can be determined during the IMS. The positions of presently orbiting heliocentric spacecraft are shown at various intervals with respect to the nominal interplanetary magnetic field spiral and the earth. Plots of the latest ISEE-A orbit in solar magnetospheric co-ordinates are presented to determine neutral-sheet crossing.

Vette, J. I.; Hilberg, R. H.; Teague, M. J.

1976-01-01

34

Photochemistry of atomic oxygen green and red-doublet emissions in comets at larger heliocentric distances  

NASA Astrophysics Data System (ADS)

Context. In comets, the atomic oxygen green (5577 Å) to red-doublet (6300, 6364 Å) emission intensity ratio (G/R ratio) of 0.1 has been used to confirm H2O as the parent species producing forbidden oxygen emission lines. The larger (>0.1) value of G/R ratio observed in a few comets is ascribed to the presence of higher CO2 and CO relative abundances in the cometary coma. Aims: We aim to study the effect of CO2 and CO relative abundances on the observed G/R ratio in comets observed at large (>2 au) heliocentric distances by accounting for important production and loss processes of O(1S) and O(1D) atoms in the cometary coma. Methods: Recently we have developed a coupled chemistry-emission model to study photochemistry of O(1S) and O(1D) atoms and the production of green and red-doublet emissions in comets Hyakutake and Hale-Bopp. In the present work we applied the model to six comets where green and red-doublet emissions are observed when they are beyond 2 au from the Sun. Results: The collisional quenching of O(1S) and O(1D) can alter the G/R ratio more significantly than that due to change in the relative abundances of CO2 and CO. In a water-dominated cometary coma and with significant (>10%) CO2 relative abundance, photodissociation of H2O mainly governs the red-doublet emission, whereas CO2 controls the green line emission. If a comet has equal composition of CO2 and H2O, then ~50% of red-doublet emission intensity is controlled by the photodissociation of CO2. The role of CO photodissociation is insignificant in producing both green and red-doublet emission lines and consequently in determining the G/R ratio. Involvement of multiple production sources in the O(1S) formation may be the reason for the observed higher green line width than that of red lines. The G/R ratio values and green and red-doublet line widths calculated by the model are consistent with the observation. Conclusions: Our model calculations suggest that in low gas production rate comets the G/R ratio greater than 0.1 can be used to constrain the upper limit of CO2 relative abundance provided the slit-projected area on the coma is larger than the collisional zone. If a comet has equal abundances of CO2 and H2O, then the red-doublet emission is significantly (~50%) controlled by CO2 photodissociation and thus the G/R ratio is not suitable for estimating CO2 relative abundance.

Raghuram, Susarla; Bhardwaj, Anil

2014-06-01

35

Orbital acrobatics in the Sun-Earth-Moon system  

NASA Technical Reports Server (NTRS)

Unconventional trajectory techniques for space missions in the Sun-Earth-Moon system, including libration-point orbits, gravity-assist maneuvers, and Earth-return trajectories are reviewed. The ISEE-3/ICE flight experience is used to illustrate the utility of libration-point orbits called halo-orbits. Five lunar gravity-assist maneuvers used by the ISEE-3/ICE spacecraft are discussed. The final lunar swingby sent the spacecraft into a heliocentric trajectory that will eventually intercept Comet Giacobini-Zinner. As an example of the Earth-return trajectory concept, a proposed mission that includes flybys of three comets and two asteroids is described.

Farquhar, Robert W.; Dunham, D. W.; Hsu, S. C.

1986-01-01

36

A dynamical analysis of the dust tail of Comet C/1995 O1 (Hale-Bopp) at high heliocentric distances  

NASA Astrophysics Data System (ADS)

Comet C/1995 O1 (Hale-Bopp) has provided an unprecedented opportunity to observe a bright comet over a wide range of heliocentric distances. We present here Spitzer Space Telescope observations of Hale-Bopp from 2005 to 2008 that show a distinct coma and tail, the presence of which is uncommon given its large heliocentric distance (21.6 AU and 27.2 AU, respectively). The morphology of the dust is compared to dynamical models to understand the activity of the comet. Our analysis shows that the shape of Hale-Bopp’s dust tail in these images cannot be explained using the usual Finson-Probstein (solar gravity + solar radiation pressure) dynamical model. Several alternative explanations are explored. The analysis suggests that the most likely cause of the discrepancy is that the dust is being charged by the solar wind, then being affected by the interplanetary magnetic field via the Lorentz force. Though this effect has been explored previously, if correct, this seems to be the first time that the Lorentz force has been required to model a cometary dust tail. The analysis also suggests that Hale-Bopp was actively emitting particles when these images were taken, and the tail characteristics changed between observations.

Kramer, Emily A.; Fernandez, Yanga R.; Lisse, Carey M.; Kelley, Michael S. P.; Woodney, Laura M.

2014-07-01

37

Proton temperature change with heliocentric distance from 0.3 to 1 AU according to relative temperatures  

NASA Astrophysics Data System (ADS)

Helios spacecraft data excluding shocks, ejecta, and low-cadence plasma intervals are averaged into hour-long intervals and binned by heliocentric distance. In each distance bin, relative classes of fluctuation-normalized cross helicity and total energy are made with a further refinement of each of these classes according to the relative proton radial component of temperature. The relative classes of temperature itself are also examined. All temperatures in each class are fitted by a power law as a function of heliocentric distance to determine the power law index. The difference between this index and the adiabatic index for isotropic plasma can be the first-order indicator of heat addition to the plasma. Relative total energy has temperature indices and behaviors that can be consistent with heat addition from a turbulent energy cascade. Relative cross helicity also shows indices that can support heat addition, but the results are inconclusive on heat addition, especially at high cross helicity. A detailed knowledge of the thermal anisotropy, at least, is required in the case of high cross helicity.

Lamarche, Leslie J.; Vasquez, Bernard J.; Smith, Charles W.

2014-05-01

38

Method of determining the orbits of the small bodies in the solar system based on an exhaustive search of orbital planes  

NASA Astrophysics Data System (ADS)

A universal method of determining the orbits of newly discovered small bodies in the Solar System using their positional observations has been developed. The proposed method suggests determining geocentric distances of a small body by means of an exhaustive search for heliocentric orbital planes and subsequent determination of the distance between the observer and the points at which the chosen plane intersects with the vectors pointing to the object. Further, the remaining orbital elements are determined using the classical Gauss method after eliminating those heliocentric distances that have a fortiori low probabilities. The obtained sets of elements are used to determine the rms between the observed and calculated positions. The sets of elements with the least rms are considered to be most probable for newly discovered small bodies. Afterwards, these elements are improved using the differential method.

Bondarenko, Yu. S.; Vavilov, D. E.; Medvedev, Yu. D.

2014-05-01

39

The effects of outgassing jets on the rotation of a comet nucleus and on the trajectory of an orbiting spacecraft  

Microsoft Academic Search

An outgassing jet model is presented in this thesis in support of spacecraft navigation for future missions to comets. The outgassing jet is modelled as an emission cone while the comet nucleus is modelled as a uniform density triaxial ellipsoid. The heliocentric orbit motion as well as in the strength of the outgassing jet are accounted for in the equations

Sharyl M. Byram

2009-01-01

40

Orbital pseudotumor  

MedlinePLUS

Orbital pseudotumor is a swelling of the tissues behind the eye in an area called the orbit. The ... and tissue that surround it. Unlike cancerous tumors, orbital pseudotumor does not spread to other tissues or places ...

41

Analysis and interpretation of CCD data on P/Halley and physical parameters and activity status of cometary nuclei at large heliocentric distance  

NASA Technical Reports Server (NTRS)

The scientific objectives were as follows: (1) to construct a well sampled photometric time series of comet Halley extending to large heliocentric distances both post and pre-perihelion passage and derive a precise ephemeris for the nuclear spin so that the physical and chemical characteristics of individual regions of activity on the nucleus can be determined; and (2) to extend the techniques in the study of Comet Halley to the study of other cometary nuclei and to obtain new observational data.

Belton, Michael J. S.; Mueller, Beatrice

1991-01-01

42

A STUDY OF THE HELIOCENTRIC DEPENDENCE OF SHOCK STANDOFF DISTANCE AND GEOMETRY USING 2.5D MAGNETOHYDRODYNAMIC SIMULATIONS OF CORONAL MASS EJECTION DRIVEN SHOCKS  

SciTech Connect

We perform four numerical magnetohydrodynamic simulations in 2.5 dimensions (2.5D) of fast coronal mass ejections (CMEs) and their associated shock fronts between 10 Rs and 300 Rs. We investigate the relative change in the shock standoff distance, {Delta}, as a fraction of the CME radial half-width, D {sub OB} (i.e., {Delta}/D {sub OB}). Previous hydrodynamic studies have related the shock standoff distance for Earth's magnetosphere to the density compression ratio (DR; {rho} {sub u}/{rho} {sub d}) measured across the bow shock. The DR coefficient, k {sub dr}, which is the proportionality constant between the relative standoff distance ({Delta}/D {sub OB}) and the compression ratio, was semi-empirically estimated as 1.1. For CMEs, we show that this value varies linearly as a function of heliocentric distance and changes significantly for different radii of curvature of the CME's leading edge. We find that a value of 0.8 {+-} 0.1 is more appropriate for small heliocentric distances (<30 Rs) which corresponds to the spherical geometry of a magnetosphere presented by Seiff. As the CME propagates its cross section becomes more oblate and the k {sub dr} value increases linearly with heliocentric distance, such that k {sub dr} = 1.1 is most appropriate at a heliocentric distance of about 80 Rs. For terrestrial distances (215 Rs) we estimate k {sub dr} = 1.8 {+-} 0.3, which also indicates that the CME cross-sectional structure is generally more oblate than that of Earth's magnetosphere. These alterations to the proportionality coefficients may serve to improve investigations into the estimates of the magnetic field in the corona upstream of a CME as well as the aspect ratio of CMEs as measured in situ.

Savani, N. P. [University Corporation for Atmospheric Research (UCAR), Boulder, CO 80307 (United States); Shiota, D. [Computational Astrophysics Laboratory, Advanced Science Institute, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Kusano, K. [Solar-Terrestrial Environment Laboratory, Nagoya University, Nagoya 464-8601 (Japan); Vourlidas, A. [Space Science Division, Naval Research Laboratory, Washington, DC 20375-5352 (United States); Lugaz, N., E-mail: neel.savani02@imperial.ac.uk [Experimental Space Plasma Group, University of New Hampshire, Durham, NH 03824 (United States)

2012-11-10

43

Numerical investigation of planetesimal collision trajectories with a Moon accumulating in Earth orbit  

SciTech Connect

In the scenario of lunar origin in which the Moon is assumed to have accreted most of its mass while in orbit about the Earth, planetasimals on the accretion knowledge of the relative impact rates of heliocentric planetting Earth and Moon is essential for any attempt to establish dynamical constraints on lunar origin. Numerical integrations of the regularized equations of motion for four bodies (Sun, Earth, Moon, planetismal) were done. A planetismal impact trajectory was calculated by assuming that the planetismal has hit the surface of the Moon at an assumed location, traveling in an assumed direction, and with an assumed impact speed. Next, the equations of motion were numerically integrated backward in time in order to determine from where the planetismal has come. In this way those volumes in heliocentric orbital element space which contribute trajectories that directly impact the Moon.

Cox, L.P.

1984-01-01

44

Spitzer Space Telescope in-orbit checkout and science verification operations  

NASA Technical Reports Server (NTRS)

Spitzer Space Telescope, the fourth and final of NASA's great observatories, and the first mission in NASA's Origins Program was launched 25 August 2003 into an Earth-trailing solar orbit. The observatory was designed to probe and explore the universe in the infrared. Before science data could be acquired, however, the observatory had to be initialized, characterized, calibrated, and commissioned. A two phased operations approach was defined to complete this work. These phases were identified as In-Orbit Checkout (IOC) and Science Verification (SV). Because the observatory lifetime is cryogen-limited these operations had to be highly efficient. The IOC/SV operations design accommodated a pre-defined distributed organizational structure and a complex, cryogenic flight system. Many checkout activities were inter-dependent, and therefore the operations concept and ground data system had to provide the flexibility required for a 'short turn-around' environment. This paper describes the adaptive operations system design and evolution, implementation, and lessons-learned from the completion of IOC/SV.

Linick, Sue H.; Miles, John W.; Gilbert, John B.; Boyles, Carol A.

2004-01-01

45

Comet Odyssey: Comet Nucleus Orbiter  

NASA Astrophysics Data System (ADS)

Comet Odyssey is a comet nucleus orbiter mission, proposed to NASA's Discovery program in 2004. The goal of the mission is to completely characterize a cometary nucleus, both physically and compositionally, as can only be done during an extended rendezvous and not with a fast flyby. Comet Odyssey will launch in October 2009 on a Delta II 7925 and use a solar-electric powered spacecraft to effect a rendezvous with periodic comet 46P/Wirtanen in October 2013. Arrival is 96 days after perihelion at a heliocentric distance of 1.61 AU. Comet Odyssey's science payload includes narrow- and wide-angle CCD cameras, an infrared thermal imager, a gas chromatograph/mass spectrometer, an XRD/XRF dust compositional analyzer, and a dust counter and accumulation sensors. The Comet Odyssey spacecraft implementation uses a high heritage approach of flight proven and redundant hardware. The 3-engine ion propulsion subsystem is derived from that on Dawn but includes the capability for multi-engine thrusting. Comet Odyssey will approach the Wirtanen nucleus and make repeated slow flybys through the active cometary coma for a period of three months. It will then be placed in a ˜100-km radius orbit around the nucleus, with a plan to eventually orbit at 40-km altitude or less. From that altitude the narrow-angle camera will map the entire nucleus surface at 1 meter/pixel and the thermal imager will map at 19 meter/pixel. The orbital portion of the nominal mission will last 4.5 months, following the comet outward from the Sun to 3.3 AU as the comet evolves from an active to a quiescent state. En route to P/Wirtanen, the Comet Odyssey spacecraft will perform a close flyby of the 200-km diameter, G-type, main belt asteroid 19 Fortuna in January 2012 and make appropriate remote sensing observations.

Weissman, P. R.; Smythe, W. D.; Spitz, S. J.; Bernard, D. E.; Bailey, R. W.

2004-11-01

46

Pupils Produce their Own Narratives Inspired by the History of Science: Animation Movies Concerning the Geocentric-Heliocentric Debate  

NASA Astrophysics Data System (ADS)

In this paper, we present the design and application of a teaching scenario appropriate for 12-years-old pupils in the primary school aiming to a better understanding of scientific concepts and scientific methods, linking the development of individual thinking with the development of scientific ideas and facilitating a better understanding of the nature of science. The design of the instructional material supporting this scenario has been based on the study of the history of astronomy and especially on: (a) The various theories concerning the movement of Earth, our solar system and the universe. (b) Key-stories highlighting the evolutionary character of scientific knowledge as well as the cultural interrelations of science and society. The design of the teaching scenario has focused on the participation of pupils in gradually evolving discourses and practices encouraging an appreciation of aspects of the nature of science (e.g. the role of observation and hypothesis, the use of evidence, the creation and modification of models). In this case, pupils are asked to produce their own narratives: animation movies concerning the geocentric-heliocentric debate inspired by the history of science, as the animation technique presents strong expressional potential and currently has many applications in the field of educational multimedia. The research design of this current case study has been based on the SHINE research model, while data coming from pupils' animation movies, questionnaires, interviews, worksheets, story-boards and drawings have been studied and analyzed using the GNOSIS research model. Elaborated data coming from our analysis approach reveal the appearance, transformation and evolution of aspects of nature of science appreciated by pupils and presented in their movies. Data analysis shows that during the application pupils gradually consider more and more the existence of multiple answers in scientific questions, appreciate the effect of culture on the way science functions and the way scientists work as well as the effect of new scientific interpretations that replace the old ones in the light of new evidence. The development of pupils' animation movies carrying aspects of the history of astronomy with a strong focus on the understanding of the nature of science creates a dynamic educational environment that facilitates pupils' introduction to a demanding teaching content (e.g. planet, model, retrograde motion) placing it in context (key-stories from the history of science) and at the same time offers to pupils the opportunity to engage their personal habits, interests and hobbies in the development of their science movies.

Piliouras, Panagiotis; Siakas, Spyros; Seroglou, Fanny

2011-07-01

47

Kepler's Orbit  

NASA Video Gallery

Kepler does not orbit the Earth, rather it orbits the Sun in concert with the Earth, slowly drifting away from Earth. Every 61 Earth years, Kepler and Earth will pass by each other. Throughout the ...

48

Orbital pathology  

Microsoft Academic Search

This overview of orbital pathology deals with different kinds of tumors, inflammatory, vascular, and traumatic diseases, which may involve the orbit. Depending on the respective orbital compartment of the globe, the intrakonal, extrakonal and optic nerve the most important and most frequent lesions are presented with their specific clinical symptoms. Their specific presentation on CT- and MR-imaging is discussed in

W Müller-Forell; S Pitz

2004-01-01

49

Heliocentric Distance of Coronal Mass Ejections at the Time of Energetic Particle Release: Revisiting the Ground Level Enhancement Events of Solar Cycle 23  

NASA Technical Reports Server (NTRS)

Using the kinematics of coronal mass ejections (CMEs), onset time of soft X-ray flares, and the finite size of the pre-eruption CME structure, we derive the heliocentric distane at which the energetic particles during the ground level enhancement (GLE) events of Solar Cycle 23. We find that the GLE particles are released when the CMEs reach an average heliocentric distance of approx.3.25 solar radii (Rs). From this we infer that the shocks accelerating the particles are located at similar heights. Type II radio burst observations indicate that the CMEs are at much lower distances (average approx.1.4 Rs) when the CME-driven shock first forms. The shock seems to travel approx.1.8 Rs over a period of approox.30 min on the average before releasing the GLE particles. In deriving these results, we made three assumptions that have observational support: (i) the CME lift off occurs from an initial distance of about 1.25 Rs; (ii) the flare onset and CME onset are one and the same because these are two different manifestations of the same eruption; and (iii) the CME has positive acceleration from the onset to the first appearance in the coronagraphic field of view (2.5 to 6 Rs). Observations of coronal cavities in eclipse pictures and in coronagraphic images justify the assumption (i). The close relationship between the flare reconnection magnetic flux and the azimuthal flux of interplanetary magnetic clouds justify assumption (ii) consistent with the standard model (CSHKP) of solar eruption. Coronagraphic observations made close to the solar surface indicate a large positive acceleration of CMEs to a heliocentric distance of approx.3 Rs before they start slowing down due to the drag force. The inferred acceleration (approx.1.5 km/s/s) is consistent with reported values in the literature.

Gopalswamy, Natchimuthuk

2011-01-01

50

Data catalog series for space science and applications flight missions. Volume 1A: Descriptions of planetary and heliocentric spacecraft and investigations, second edition  

NASA Technical Reports Server (NTRS)

The main purpose of the data catalog series is to provide descriptive references to data generated by space science flight missions. The data sets described include all of the actual holdings of the Space Science Data Center (NSSDC), all data sets for which direct contact information is available, and some data collections held and serviced by foreign investigators, NASA and other U.S. government agencies. This volume contains narrative descriptions of planetary and heliocentric spacecraft and associated experiments. The following spacecraft series are included: Mariner, Pioneer, Pioneer Venus, Venera, Viking, Voyager, and Helios. Separate indexes to the planetary and interplanetary missions are also included.

Cameron, Winifred Sawtell (editor); Vostreys, Robert W. (editor)

1988-01-01

51

Orbital inflammation  

Microsoft Academic Search

Orbital inflammation is a common problem in adults and children, accounting for the majority of all orbital processes. The\\u000a presentation may be acute, subacute, or insidious. When the onset is acute, the process can be mistaken for orbital cellulitis.\\u000a In insidious cases, such as the sclerosing subtype of inflammation, the chronic painless course may prompt concerns about\\u000a a neoplastic infiltration

Kimberly P. Cockerham; Sang H. Hong; Ellen E. Browne

2003-01-01

52

Orbiting Earth  

NSDL National Science Digital Library

This Flash animation contrasts the geostationary versus polar orbits for satellites. For a geostationary orbit, the satellite remains directly above a fixed point at all times; in time with the Earth's rotation, the satellite circles the earth once every 24 hours, continually viewing the same part of Earth. For the polar orbit, the satellite circles over both poles in a constant plane while earth rotates beneath. Earth's rotation exposes different parts of the surface on each orbit. The animation is useful for a discussion on how remote sensing imagery and Global Positioning Systems (GPS) signals are derived. The animation can be paused and rewound to stress important points.

Loomis, Jennifer; Nasa; Earth, Exploring

53

Atomic Orbitals  

NSDL National Science Digital Library

The Atomic Orbitals Web site "was established as part of an (ongoing) project at Purdue University to develop 'visualization modules' for general chemistry students." Using the Chime plug-in, which allows unique and stunning visualizations, visitors can learn what an atomic orbital is; what the 1s, 2s, 3s, 2p, 3p, and 3d orbitals are; what hybrid orbitals are; and more. The combination of easy-to-read descriptions and educational graphics make the site a great learning resource for high school and even college level chemistry students.

1969-12-31

54

What do the orbital motions of the outer planets of the Solar System tell us about the Pioneer anomaly?  

Microsoft Academic Search

In this paper, we investigate the effects that an anomalous acceleration as that experienced by the Pioneer spacecraft after they passed the 20AU threshold would induce on the orbital motions of the Solar System planets placed at heliocentric distances of 20AU or larger as Uranus, Neptune and Pluto. It turns out that such an acceleration, with a magnitude of 8.74×10?10ms?2,

Lorenzo Iorio; Giuseppe Giudice

2006-01-01

55

The Hot Orbit: Orbital Cellulitis  

PubMed Central

Orbital cellulitis is an uncommon condition previously associated with severe complications. If untreated, orbital cellulitis can be potentially sight and life threatening. It can affect both adults and children but has a greater tendency to occur in the pediatric age group. The infection most commonly originates from sinuses, eyelids or face, retained foreign bodies, or distant soources by hematogenous spread. It is characterized by eyelid edema, erythema, chemosis, proptosis, blurred vision, fever, headache, and double vision. A history of upper respiratory tract infection prior to the onset is very common especially in children. In the era prior to antibiotics, vision loss from orbital cellulitis was a dreaded complication. Currently, imaging studies for detection of orbital abcess, the use of antibiotics and early drainage have mitigated visual morbidity significantly. The purpose of this review is to describe current investigative strategies and management options in the treatment of orbital cellulitis, establish their effectiveness and possible complications due to late intervention.

Chaudhry, Imtiaz A.; Al-Rashed, Waleed; Arat, Yonca O.

2012-01-01

56

Orbital Decompression  

MedlinePLUS

... appearance. One of the most common indications is Graves’ disease, an autoimmune disorder that primarily affects the thyroid gland and the eye. If the eye is affected (Grave’s orbitopathy), there is an enlargement of the orbital ...

57

Orbital Motion  

NSDL National Science Digital Library

Authored by Eleanor Kopsian of Franklin Frazier, this is an activity intended to help students understand orbital motion and Kepler's Laws through a comparison of a circle and an ellipse and the application of Kepler's Law of Elliptical Orbits. The lesson contains objectives, vocabulary, needed materials, strategies, handouts, conclusions, evaluation questions and references. Although simple in design, this can still be a very useful resource for an instructor looking to enhance or create new curriculum.

Kopsian, Eleanor

2009-05-27

58

A simple procedure to extend the Gauss method of determining orbital parameters from three to N points  

NASA Astrophysics Data System (ADS)

A simple procedure is developed to determine orbital elements of an object orbiting in a central force field which contribute more than three independent celestial positions. By manipulation of formal three point Gauss method of orbit determination, an initial set of heliocentric state vectors r i and is calculated. Then using the fact that the object follows the path that keep the constants of motion unchanged, I derive conserved quantities by applying simple linear regression method on state vectors r i and . The best orbital plane is fixed by applying an iterative procedure which minimize the variation in magnitude of angular momentum of the orbit. Same procedure is used to fix shape and orientation of the orbit in the plane by minimizing variation in total energy and Laplace Runge Lenz vector. The method is tested using simulated data for a hypothetical planet rotating around the sun.

Mirtorabi, Taghi

2014-01-01

59

Orbit Determination Accuracy for Comets on Earth-Impacting Trajectories  

NASA Technical Reports Server (NTRS)

The results presented show the level of orbit determination accuracy obtainable for long-period comets discovered approximately one year before collision with Earth. Preliminary orbits are determined from simulated observations using Gauss' method. Additional measurements are incorporated to improve the solution through the use of a Kalman filter, and include non-gravitational perturbations due to outgassing. Comparisons between observatories in several different circular heliocentric orbits show that observatories in orbits with radii less than 1 AU result in increased orbit determination accuracy for short tracking durations due to increased parallax per unit time. However, an observatory at 1 AU will perform similarly if the tracking duration is increased, and accuracy is significantly improved if additional observatories are positioned at the Sun-Earth Lagrange points L3, L4, or L5. A single observatory at 1 AU capable of both optical and range measurements yields the highest orbit determination accuracy in the shortest amount of time when compared to other systems of observatories.

Kay-Bunnell, Linda

2004-01-01

60

Achieving Orbit  

NSDL National Science Digital Library

This is an engineering design challenge activity. Learners will use balloons to investigate how a multi-stage rocket, like that used to launch the Interstellar Boundary Explorer, or IBEX, spacecraft, can propel a satellite to a specific orbit. Learners will construct a two-stage balloon rocket that will be required to reach a particular location on the balloon track, simulating the proper orbit around Earth to be reached by the IBEX satellite. This activity complements other IBEX informal education materials. An instructional video explaining how to facilitate this activity is available: http://bit.ly/ZwlFf4.

61

Orbital Elements  

NSDL National Science Digital Library

Coordinates for tracking the International Space Station and the Mir Space Station are available here from NASA's Johnson Space Center Flight Design and Dynamics Division. The Orbital Elements page offers real-time data for use in ground track plotting programs. The site cautions the data are for ground track plotting programs only and "should not be used for precise applications or analysis!"

62

Elliptical Orbits  

NSDL National Science Digital Library

Although not inquiry, this activity is important for students to understand what an ellipse is and what a focus is, and to break misconceptions about Earth's orbit being highly elliptical. This is the perfect place to check to see if students have the mis

Horton, Michael

2009-05-30

63

Orbital Mechanics.  

ERIC Educational Resources Information Center

Three computer programs are presented that allow the high school student to explore and understand the physical forces involved in orbital flight at a greater depth than is usually possible. For each program, introductory material is given including the physics and mathematics involved. This is followed by the computer program in BASIC language.…

Dalton, Joel B.

64

Mars Orbit  

NSDL National Science Digital Library

This geometry lesson from Illuminations uses the model of the orbits of Mars and Earth relative to the sun to illustrate parametric equations. As an interdisciplinary learning activity, the material may be used in conjunction with astronomy lessons. An interactive applet and student questions are also included. The material is intended for grades 9-12 and should require 1 class period to complete.

2010-12-14

65

Orbital Effects on Mercury's Escaping Sodium Exosphere  

NASA Technical Reports Server (NTRS)

We present results from coronagraphic imaging of Mercury's sodium tail over a 7 deg field of view. Several sets of observations made at the McDonald Observatory since May 2007 show a tail of neutral sodium atoms stretching more than 1000 Mercury radii (R(sub m)) in length, or a full degree of sky. However, no tail was observed extending beyond 120 R(sub m) during the January 2008 MESSENGER Fly-by period, or during a similar orbital phase of Mercury in July 2008. Large changes in Mercury's heliocentric radial velocity cause Doppler shifts about the Fraunhofer absorption features; the resultant change in solar flux and radiation pressure is the primary cause of the observed variation in tail brightness. Smaller fluctuations in brightness may exist due to changing source rates at the surface, but we have no explicit evidence for such changes in this data set. The effects of radiation pressure on Mercury's escaping atmosphere are investigated using seven observations spanning different orbital phases. Total escape rates of atmospheric sodium are estimated to be between 5 and 13 x 10(exp 23) atoms/s and show a correlation to radiation pressure. Candidate sources of Mercury's sodium exosphere include desorption by UV sunlight, thermal desorption, solar wind channeled along Mercury's magnetic field lines, and micro-meteor impacts. Wide-angle observations of the full extent of Mercury's sodium tail offer opportunities to enhance our understanding of the time histories of these source rates.

Schmidt, Carl A.; Wilson, Jody K.; Baumgardner, Jeffrey; Mendillo, Michael

2009-01-01

66

Orbiting Hotel  

NSDL National Science Digital Library

It is the year 2025 and a large company, Z-Tech, wants to put a hotel in space having it orbit around one of the planets in our solar system. Our 9th grade class has been given a very important job. We have to search for the perfect location for the hotel. Our job is to report back to the company with the planet that is the best place for an orbiting hotel. The Task: You are to write a report recommending which planet should be chosen. Your report should include pictures of the planet you recommended. Here are the questions you should answer in order to report back to Z-Tech with your recommendation. * Which planet will be the ...

Hicken, Mrs.

2009-10-19

67

Theory of satellite orbit-orbit resonance  

Microsoft Academic Search

On the basis of the strong mathematical and physical parallels between orbit-orbit and spin-orbit resonances, the dynamics of mutual orbit perturbations between two satellites about a massive planet are examined, exploiting an approach previously adopted in the study of spin-orbit coupling. The satellites are assumed to have arbitrary mass ratio and to move in non-intersecting orbits of arbitrary size and

Leon Blitzer; John D. Anderson

1981-01-01

68

Ar-37/Ar-39 ratios in meteorites - The flux and heliocentric radial gradient of galactic cosmic rays during last two solar cycles and the last millennium  

NASA Astrophysics Data System (ADS)

Ratios between the cosmogenic Ar-37 and Ar-39 activities in meteorites are used to estimate the long-term heliocentric gradient in galactic cosmic ray intensities, and changes in intensities between the last two solar cycles and the last millenium. Comparisons of past galactic cosmic ray intensities deduced from sunspot records with experimental measurements of the Ar-37/Ar-39 ratios in the Fe plus Ni phases of 19 meteorites fallen between 1959 and 1977 indicate a 20 percent greater flux over the past millenium, when Ar-39 was formed, than over the past two solar cycles, when the measured Ar-37 was produced. Results are also consistent with a radial gradient in galactic cosmic ray flux of less than 5 percent/AU between 1 and 2.8 AU for particle energies of 1 to 2 GeV. An important decrease in galactic cosmic rays in the vicinity of the earth during the solar maximum of 1969-1971 is also indicated.

Bibron, R.; Leger, C.; Tobailem, J.; Yokoyama, Y.

69

Inflammation of the Orbit  

MedlinePLUS

... Socket Disorders 4 Inflammation of the Orbit (Inflammatory Orbital Pseudotumor) Any or all of the structures within the ... entire orbit and its contents is called inflammatory orbital pseudotumor (which is not really a tumor and is ...

70

Fast Geometric Method for Calculating Accurate Minimum Orbit Intersection Distances (MOIDs)  

NASA Astrophysics Data System (ADS)

We present a new method to compute Minimum Orbit Intersection Distances (MOIDs) for arbitrary pairs of heliocentric orbits and compare it with Giovanni Gronchi's algebraic method. Our procedure is numerical and iterative, and the MOID configuration is found by geometric scanning and tuning. A basic element is the meridional plane, used for initial scanning, which contains one of the objects and is perpendicular to the orbital plane of the other. Our method also relies on an efficient tuning technique in order to zoom in on the MOID configuration, starting from the first approximation found by scanning. We work with high accuracy and take special care to avoid the risk of missing the MOID, which is inherent to our type of approach. We demonstrate that our method is both fast, reliable and flexible. It is freely available and its source Fortran code downloadable via our web page.

Wi?niowski, T.; Rickman, H.

2013-06-01

71

Small orbits  

NASA Astrophysics Data System (ADS)

We study both the large and small U-duality charge orbits of extremal black holes appearing in D=5 and D=4 Maxwell-Einstein supergravity theories with symmetric scalar manifolds. We exploit a formalism based on cubic Jordan algebras and their associated Freudenthal triple systems, in order to derive the minimal charge representatives, their stabilizers and the associated “moduli spaces.” After recalling N=8 maximal supergravity, we consider N=2 and N=4 theories coupled to an arbitrary number of vector multiplets, as well as N=2 magic, STU, ST2 and T3 models. While the STU model may be considered as part of the general N=2 sequence, albeit with an additional triality symmetry, the ST2 and T3 models demand a separate treatment, since their representative Jordan algebras are Euclidean or only admit nonzero elements of rank 3, respectively. Finally, we also consider minimally coupled N=2, matter-coupled N=3, and pure N=5 theories.

Borsten, L.; Duff, M. J.; Ferrara, S.; Marrani, A.; Rubens, W.

2012-04-01

72

Shapes of d Orbitals  

NSDL National Science Digital Library

Shapes of d Orbitals shows the d orbitals in an axis set. Running the mouse over an orbital reveals the "name" of that orbital. This is good practice for helping students link the name of an orbital to the orientation.Shapes of d Orbitals has a link to D Orbitals in an Octahedral Ligand Field. Here the user may click on the name of any one of the d orbitals to obtain a larger 3-dimensional image. The images are rotatable and scalable. Orbital phase is shown by the different colors.

73

Orbital Propellant Depot  

NASA Technical Reports Server (NTRS)

In this artist's concept from 1971, an Earth-to orbit fuel tanker approaches the Orbital Propellant Depot. As envisioned by Marshall Space Flight Center Program Devlopment plarners, an orbital modular propellant storage depot, supplied periodically by the Space Shuttle or Earth-to-orbit fuel tankers would be critical in making available large amounts of fuel to various orbital vehicles and spacecraft.

1971-01-01

74

What is orbital pseudotumor?  

Microsoft Academic Search

We have reviewed the literature in order to delineate the clinicopathologic definition of orbital pseudotumor, also called idiopathic nonspecific orbital inflammation. The clinical picture of orbital pseudotumor varies widely, with signs of mass effect, inflammation and\\/or infiltration. On computed tomography, orbital pseudotumor presents as a unilateral focal or diffuse mass. The histopathologic hallmark of orbital pseudotumor is a mixed inflammatory

Ilse Mombaerts; Roel Goldschmeding; Reinier O. Schlingemann; Leo Koornneef

1996-01-01

75

NASA's Spitzer Space Telescope's Operational Mission Experience  

NASA Technical Reports Server (NTRS)

New Generation of Detector Arrays(100 to 10,000 Gain in Capability over Previous Infrared Space Missions). IRAC: 256 x 256 pixel arrays operating at 3.6 microns, 4.5 microns, 5.8 microns, 8.0 microns. MIPS: Photometer with 3 sets of arrays operating at 24 microns, 70 microns and 160 microns. 128 x 128; 32 x 32 and 2 x 20 arrays. Spectrometer with 50-100 micron capabilities. IRS: 4 Array (128x128 pixel) Spectrograph, 4 -40 microns. Warm Launch Architecture: All other Infrared Missions launched with both the telescope and scientific instrument payload within the cryostat or Dewar. Passive cooling used to cool outer shell to approx.40 K. Cryogenic Boil-off then cools telescope to required 5.5K. Earth Trailing Heliocentric Orbit: Increased observing efficiency, simplification of observation planning, removes earth as heat source.

Wilson, Robert K.; Scott, Charles P.

2006-01-01

76

Orbital Evolution and Migration of Extrasolar Planets  

NASA Astrophysics Data System (ADS)

Giant planets in circumstellar disks can migrate inward from their initial (formation) positions. Migration is caused by inward torques between the planet and the disk; by outward torques between the planet and the spinning star; and by outward torques due to Roche lobe overflow and mass loss from the planet. Summing torques on planets in disks with various physical parameters, we find that Jupiter-mass planets can stably arrive and survive at small heliocentric distances. Inward migration timescales can be approximately equal to or less than disk lifetimes and star spindown timescales. Therefore, the range of fates of Jupiter-mass planets is broad, and generally comprises three classes: (I) planets which migrate inward too rapidly and lose all their mass due to Roche lobe overflow; (II) planets which migrate inward and survive in very small orbits; and (III) planets which do not migrate very far. Some, but not all, of the planets in Class II lose mass during their evolution and migration times, resulting in planets with final masses smaller than their initial masses. For example, in our model, we produce planets similar to 51 Peg b which have lost ~ 75% of their initial mass. The observed extrasolar planets, both those with extremely small semi-major axes (51 Peg b at 0.05 AU, tau Boo b (0.046 AU), upsilon And b (0.057 AU), and 55 Cnc b (0.11 AU)) and those with more moderate semi-major axes (rho Cor Bor b (0.23 AU), 47 UMa b (2.1 AU)) form a subset of the potential outcomes of the system, in that Jupiter-mass objects can stably survive in orbits with a wide range of semi-major axes. Our numerical model produces planets which have similar characteristics to the observed planets, as well as planets similar to Jupiter, and many intermediate cases. Since Jupiters can stably migrate to various orbital separations, we predict that, as planetary detection techniques improve, Jupiter-mass planets will be found in a wide range of orbits, from much less than 1 AU to several AU or more.

Trilling, D. E.; Benz, W.; Guillot, T.; Lunine, J. I.; Hubbard, W. B.; Burrows, A.

1997-07-01

77

Statistical initial orbit determination  

Microsoft Academic Search

For the ballistic missile initial orbit determination problem in particular, the concept of 'launch folders' is extended. This allows to decouple the observational data from the initial orbit determination problem per se. The observational data is only used to select among the possible orbital element sets in the group of folders. Monte Carlo simulations using up to 7200 orbital element

L. G. Taff; B. Belkin; G. A. Schweiter; K. Sommar

1992-01-01

78

A study of halo orbits at the Sun-Mars L1 Lagrangian point in the photogravitational restricted three-body problem  

NASA Astrophysics Data System (ADS)

Photogravitational Restricted Three-Body Problem (PGRTBP) is considered and halo orbits are generated in the vicinity of the Sun-Mars L1 Lagrangian point. Deviation of properties such as time period, size and velocity variation in the halo orbits with Sun as a source of radiation are discussed. With increase in solar radiation pressure, the halo orbits are found to elongate and move towards the Sun and the time period of the halo orbits is found to increase. The variation in the behaviour of invariant manifolds with change in radiation pressure is also computed and it is found that as the radiation pressure increases, the transition from Mars-centric path to heliocentric path is delayed. Certain implications of the velocity profile of the invariant manifolds are also discussed.

Eapen, Roshan Thomas; Sharma, Ram Krishan

2014-05-01

79

Interactive Molecular Orbitals  

NSDL National Science Digital Library

The majority of Introductory Chemistry texts provide students with an adequate introduction to the visual aspects of the molecular orbital model for homonuclear diatomic molecules. The treatment of heteronuclear diatomic and polyatomic molecules is less uniform. Heteronuclear diatomics, when mentioned, are invariably treated as being derived from homonuclear diatomics. While the atomic orbital energy level differences in heteronuclear diatomics is sometimes pictured, the consequences of those differences for the resultant molecular orbitals are rarely discussed. The discussion of polyatomic molecular orbitals in these texts is limited to showing that parallel p-orbitals produce delocalized pi molecular orbitals. The molecules typically mentioned in this context are benzene, nitrate ion and carbonate ion. However, It is rarely pointed out that the six p-orbitals in benzene would form 6 pi molecular orbitals, and that only one of these orbitals would look like the picture in the text.These interactive modules are designed to clarify this subject.

80

Fibrolipoma of the orbit.  

PubMed

A 47-year-old woman presented with a growing mass on the lateral rim of orbit. Orbital CT revealed a well-circumscribed soft tissue mass in the right lateral orbit, with focal hyperostosis of the adjacent zygomatic bone. MRI showed a lesion of mixed T1-signal intensity, which became hypointense after fat suppression. The lesion was excised, and the diagnosis of orbital fibrolipoma was made by histopathologic examination. There was no evidence of tumor after 12 months of follow-up. Orbital fibrolipoma is a rare variant of lipoma, with only 1 case described previously. It should be considered in the differential diagnosis of orbital mass. PMID:20700070

Kim, Myung Hun; Sa, Ho Seok; Woo, Kyung; Kim, Yoon-Duck

2011-01-01

81

Lunar orbiting prospector  

NASA Technical Reports Server (NTRS)

One of the prime reasons for establishing a manned lunar presence is the possibility of using the potential lunar resources. The Lunar Orbital Prospector (LOP) is a lunar orbiting platform whose mission is to prospect and explore the Moon from orbit in support of early lunar colonization and exploitation efforts. The LOP mission is divided into three primary phases: transport from Earth to low lunar orbit (LLO), operation in lunar orbit, and platform servicing in lunar orbit. The platform alters its orbit to obtain the desired surface viewing, and the orbit can be changed periodically as needed. After completion of the inital remote sensing mission, more ambitious and/or complicated prospecting and exploration missions can be contemplated. A refueled propulsion module, updated instruments, or additional remote sensing packages can be flown up from the lunar base to the platform.

1988-01-01

82

Atomic Orbital Shapes  

NSDL National Science Digital Library

This applet shows 3-dimensional representations of hydrogenic orbital surfaces. Orbital phase is shown by the different colors. The images are rotatable and scalable. This applet will run very slowly on older, slower machines.

83

Harmonically Excited Orbital Variations.  

National Technical Information Service (NTIS)

Rephrasing the equations of motion for orbital maneuvers in terms of Lagrangian generalized coordinates instead of Newtonian rectangular cartesian coordinates can make certain harmonic terms in the orbital angular momentum vector more readily apparent. In...

T. Morgan

1985-01-01

84

Orbiting Binary Stars  

NSDL National Science Digital Library

This simulation demonstrates the path of binary stars' orbit. The user is able to set the masses, orbital separation, orbital eccentricity, the inclination angle to our line of sight, and the angle of the nodes of two orbiting stars. The observed velocities of the two stars, and the Doppler shifted spectral lines are also shown in the upper right box. The site also includes definitions of terms used, instructions on how to use the simulation and a few examples.

Kolena, John

2007-12-11

85

Mars orbit selection  

NASA Technical Reports Server (NTRS)

Parking orbits for a manned Mars mission are examined for ease of access to the Martian moons. Delta V plots for a variety of burns versus elliptical orbit apoapsis are included. A high elliptical orbit (24 hour period, 500 km periapsis, 20 to 30 deg. inclination) minimizes delta V to the Martian moons and Mars orbit insertion (MOI) and trans-Earth injection (TEI) delta Vs.

Babb, Gus R.; Stump, William R.

1986-01-01

86

Pathologies of the Orbit  

Microsoft Academic Search

Pathologic lesions of the orbit continue to be a great challenge to the diagnostic radiologist. The complex anatomy of the\\u000a orbit on the one hand and the multitude of disease entities that may affect the orbit on the other hand demand a simple, well-structured\\u000a approach to diagnostic imaging. Subdividing the orbit into four (or five) distinct spaces, i.e., the eyeball,

Ullrich G. Mueller-Lisse; JuerGen Lutz

87

Arietid Meteor Orbits Measurements  

NASA Astrophysics Data System (ADS)

The Arietid meteor shower is one of the strongest of the year. The origin of this daytime shower is unknown; the orbit is therefore of great interest, since an accurate orbit distribution is needed to integrate the shower backward in time to test associations with comets or asteroids. The orbital parameters of the Arietid shower as a function of time, with errors, have been generated using 415 radar orbits gathered at the CMOR facility in Tavistock, Canada.

Campbell-Brown, M. D.

2004-12-01

88

Orbits of Photographic Meteors  

Microsoft Academic Search

New photographic observations of meterors in the brightness range-5 > Mp > -18 (?) and with a median value of M = -8.5 have yielded orbits with a precision of better than 1° in the angular elements and of about 0.05 in e and 1\\/a. A comparison of 100 of these fireball orbits with Super-Schmidt orbits shows: A. A class

R. E. McCrosky

1967-01-01

89

Orbital-Lifetime Program  

NASA Technical Reports Server (NTRS)

Orbital Lifetime Program (OL) analyzes long-term motion of Earthorbiting spacecraft at altitudes of up to 2,500 km. Models perturbations to orbit caused by solar-radiation pressure, atmospheric drag, and gravitational effects of Sun, Moon, and oblate Earth. Used to predict orbital lifetime and decay rate of satellites. OL written in FORTRAN 77.

Orr, L. H.

1986-01-01

90

SEASAT B orbit synthesis  

NASA Technical Reports Server (NTRS)

Addition were made to Battelle's Interactive Graphics Orbit Selection (IGOS) program; IGOS was exercised via telephone lines from JPL, and candidate SEASAT orbits were analyzed by Battelle. The additions to the program enable clear understanding of the implications of a specific orbit to the diverse desires of the SEASAT user community.

Rea, F. G.; Warmke, J. M.

1976-01-01

91

Statistical initial orbit determination  

Microsoft Academic Search

The computation of a meaningful initial orbital element set based on angles- only data is abandoned as a futile endeavor. Rather, for the ballistic missile initial orbit determination problem in particular, the concept of 'launch folders' is extended. This allows one to decouple the observational data from the initial orbit determination problem per se. The observational data is only used

Laurence G. Taff; Barry Belkin; G. A. Schweiter; K. Sommar

1991-01-01

92

Five Equivalent d Orbitals  

ERIC Educational Resources Information Center

Amplifies and clarifies a previous paper on pyramidal d orbitals. Discusses two sets of pyramid d orbitals with respect to their maximum bond strength and their symmetry. Authors described the oblate and prolate pentagonal antiprisms arising from the two sets of five equivalent d orbitals. (RR)

Pauling, Linus; McClure, Vance

1970-01-01

93

Idiopathic sclerosing orbital inflammation  

Microsoft Academic Search

Objective: To perform a multicenter review of the clinical features and treatment of 31 patients with idiopathic sclerosing orbital inflammation. Methods: We included all patients with histologically confirmed idiopathic sclerosing orbital inflammation from 5 regional orbital centers. We reviewed the case notes to determine the clinical presentation, diagnostic features, and response to treatment. The main outcome measures were duration and

James D. Hsuan; Dinesh Selva; Alan A. McNab; Timothy J. Sullivan; Peerooz Saeed; Brett A. O'Donnell

2006-01-01

94

Orbital cavernous hemangiomas  

Microsoft Academic Search

Cavernous hemangiomas are the most frequently found primary tumors in the orbital region. They normally appear in adults. Diagnostic features in the majority of cases include protrusio bulbi and orbital enlargement. B-Scan and computed tomography\\/MRI are the prime diagnostic aids. We recommend surgical removal of these tumors, at least in cases with marked orbital protrusion or significant optic nerve compression.

Thomas Herter; Harald Bennefeld; Matthias Brandt

1988-01-01

95

Orbit Software Suite  

NASA Technical Reports Server (NTRS)

Orbit Software Suite is used to support a variety of NASA/DM (Dependable Multiprocessor) mission planning and analysis activities on the IPS (Intrusion Prevention System) platform. The suite of Orbit software tools (Orbit Design and Orbit Dynamics) resides on IPS/Linux workstations, and is used to perform mission design and analysis tasks corresponding to trajectory/ launch window, rendezvous, and proximity operations flight segments. A list of tools in Orbit Software Suite represents tool versions established during/after the Equipment Rehost-3 Project.

Osgood, Cathy; Williams, Kevin; Gentry, Philip; Brownfield, Dana; Hallstrom, John; Stuit, Tim

2012-01-01

96

Superior orbital fissure syndrome  

PubMed Central

A patient is described with features of a superior orbital fissure (Tolosa Hunt) syndrome and a coexistent intraorbital lesion. There was radiological evidence both of narrowing of the carotid artery and of an intraorbital obstruction of venous return from the orbit. The diagnostic value of orbital venography and carotid angiography in the investigation of granulomata in the region of the orbit is stressed. The condition described here is responsive to corticosteroids and it is also inferred that there may be a clinicopathological spectrum encompassing both the Tolosa Hunt syndrome and pseudotumour of the orbit. Images

Hallpike, J. F.

1973-01-01

97

Orbit correction in an orbit separated cyclotron  

NASA Astrophysics Data System (ADS)

The orbit separated proton cyclotron (OSC) described in [1] differs in concept from that of a separated orbit cyclotron (SOC) [2]. Synchronous acceleration in an OSC is based on harmonic number jumps and orbit length adjustments via reverse bending. Four-turn acceleration in the OSC enables it to have four times fewer cryogenic-cavity systems than in a superconducting linac of the same high beam power and energy range. Initial OSC studies identified a progressive distortion of the spiral beam orbits by the off-axis, transverse deflecting fields in its accelerating cavities. Compensation of the effects of these fields involves the repeated use of a cavity field map, in a 3-D linac tracking code, to determine the modified arc bends required for the OSC ring. Subsequent tracking studies confirm the compensation scheme and show low emittance growth in acceleration.

Plostinar, C.; Rees, G. H.

2014-04-01

98

Painless orbital myositis.  

PubMed

Idiopathic orbital inflammation is the third most common orbital disease, following Graves orbitopathy and lymphoproliferative diseases. We present a 11 year old girl with 15 days history of painless diplopia. There was no history of fluctuation of symptoms, drooping of eye lids or diminished vision. She had near total restricted extra-ocular movements and mild proptosis of the right eye. There was no conjunctival injection, chemosis, or bulb pain. There was no eyelid retraction or lid lag. Rest of the neurological examination was unremarkable.Erythrocyte sedimentation rate was raised with eosinophilia. Antinuclear antibodies were positive. Liver, renal and thyroid functions were normal. Antithyroid, double stranded deoxyribonucleic acid and acetylcholine receptor antibodies were negative. Repetitive nerve stimulation was negative. Magnetic resonance imaging (MRI) of the orbit was typical of orbital myositis. The patient responded to oral steroids. Orbital myositis can present as painless diplopia. MRI of orbit is diagnostic in orbital myositis. PMID:22919201

Chakor, Rahul T; Santhosh, N S

2012-07-01

99

Long-Period Meteor Streams and the Dispersion of Semimajor Axes of Meteor Orbits  

NASA Astrophysics Data System (ADS)

The present work is based on an analysis of a large statistical sample of meteor orbits collected in the Japanese shower catalogue (SonotaCo 2009, WGN, 37, 55) of 114280 video observed meteors. The shower meteor data were selected and analysed with the aim of determining the orbits' distribution in major meteor streams with heliocentric velocities close to the parabolic limit, in which the errors in the velocity determination correspond to large differences in the reciprocal semimajor axis, 1/a. The contribution of the real dispersion of the semimajor axes, a, can be deduced from the high proportion of hyperbolic orbits in the analysed streams, where an excess over the parabolic value can be regarded as being entirely due to measurement errors. The orbital dispersion described by the median absolute deviation in terms of 1/a was found to be ±0.083 AU-1 for the Leonids and ±0.080 AU-1 for the Orionids, and slightly smaller for the Perseid and Lyrid meteor streams (±0.055 and ±0.047 AU-1). The proximity of the parabolic limit caused a strong influence of observational effects; however, a significant contribution of the real dispersion is involved.

Hajduková, Mária, Jr.

2013-06-01

100

Neonatal orbital abscess  

PubMed Central

Orbital complications due to ethmoiditis are rare in neonates. A case of orbital abscess due to acute ethmoiditis in a 28-day-old girl is presented. A Successful outcome was achieved following antimicrobial therapy alone; spontaneous drainage of the abscess occurred from the lower lid without the need for surgery. From this case report, we intend to emphasize on eyelid retraction as a sign of neonatal orbital abscess, and to review all the available literature of similar cases.

Al-Salem, Khalil M; Alsarayra, Fawaz A; Somkawar, Areej R

2014-01-01

101

Orbital Debris: A Chronology  

NASA Technical Reports Server (NTRS)

This chronology covers the 37-year history of orbital debris concerns. It tracks orbital debris hazard creation, research, observation, experimentation, management, mitigation, protection, and policy. Included are debris-producing, events; U.N. orbital debris treaties, Space Shuttle and space station orbital debris issues; ASAT tests; milestones in theory and modeling; uncontrolled reentries; detection system development; shielding development; geosynchronous debris issues, including reboost policies: returned surfaces studies, seminar papers reports, conferences, and studies; the increasing effect of space activities on astronomy; and growing international awareness of the near-Earth environment.

Portree, Davis S. F. (Editor); Loftus, Joseph P., Jr. (Editor)

1999-01-01

102

Ghost orbit spectroscopy  

NASA Astrophysics Data System (ADS)

Direct periodic-orbit expansions of individual spectral eigenvalues is a new direction in quantum mechanics. Using a unitary S -matrix theory, we present exact, convergent, integral-free ghost orbit expansions of spectral eigenvalues for a step potential in the tunneling regime. We suggest an experiment to extract ghost orbit information from measured spectra in the tunneling regime (ghost orbit spectroscopy). We contrast our unitary, convergent theory with a recently published nonunitary, divergent theory [Yu. Dabaghian and R. Jensen, Eur. J. Phys. 26, 423 (2005)].

Bhullar, A. S.; Blümel, R.; Koch, P. M.

2006-01-01

103

Magnetospheric Multiscale (MMS) Orbit  

NASA Video Gallery

This animation shows the orbits of Magnetospheric Multiscale (MMS) mission, a Solar-Terrestrial Probe mission comprising of four identically instrumented spacecraft that will study the Earth's magn...

104

Family of Orbiters  

NASA Technical Reports Server (NTRS)

This image shows the paths of three spacecraft currently in orbit around Mars, as well as the path by which NASA's Phoenix Mars Lander will approach and land on the planet. The t-shaped crosses show where the orbiters will be when Phoenix enters the atmosphere, while the x-shaped crosses show their location at landing time.

All three orbiters, NASA's Mars Reconnaissance Orbiter, NASA's Mars Odyssey and the European Space Agency's Mars Express, will be monitoring Phoenix during the final steps of its journey to the Red Planet.

Phoenix will land just south of Mars's north polar ice cap.

2008-01-01

105

Mars Geoscience Orbiter and Lunar Geoscience Orbiter.  

National Technical Information Service (NTIS)

The feasibility of using the AE/DE Earth orbiting spacecraft design for the LGO and/or MGO missions was determined. Configurations were developed and subsystems analysis was carried out to optimize the suitability of the spacecraft to the missions. The pr...

W. V. Fuldner P. F. Kaskiewicz

1983-01-01

106

Satellite orbit determination  

Microsoft Academic Search

Statistical methods for determining satellite trajectories after being put into orbit, after changes in the trajectory and at regular intervals during orbital lifetime are outlined. The least squares method, a differential Gauss-Newton correction algorithm, and interpretation of the results are introduced.

P. Legendre

1984-01-01

107

Saturn Orbiter Mission Study.  

National Technical Information Service (NTIS)

A preliminary analysis of the important aspects of missions orbiting the planet Saturn is provided. Orbital missions to Saturn is given serious consideration for the 1980's, or after flybys by Pioneer 10/G and Mariner Jupiter-Saturn 1977. An attempt is ma...

W. C. Wells R. J. Sullivan

1973-01-01

108

MRI of orbital schwannomas.  

PubMed

The literature on MRI of orbital schwannomas is limited. The appearances in three patients with an orbital schwannoma were reviewed. A superior orbitotomy through a subfrontal craniotomy revealed a schwannoma in all cases. MRI characteristics of very low signal on T1-weighted images and homogeneous postcontrast enhancement may be helpful for differentiating schwannomas from other intraconal masses. PMID:10929312

Abe, T; Kawamura, N; Homma, H; Sasaki, K; Izumiyama, H; Matsumoto, K

2000-06-01

109

Noninteger Slater orbital calculations  

Microsoft Academic Search

In order to calculate the one- and two-electron, two-center integrals over non-integer n Slater type orbitals, use is made of elliptical coordinates for the monoelectronic, hybrid, and Coulomb integrals. For the exchange integrals, the atomic orbitals are translated to a common center. The final integration is performed by Gaussian quadrature.

Alain Allouche

1976-01-01

110

Orbital trapdoor fractures  

PubMed Central

Orbital trapdoor fractures are commonly encountered in children. Awareness of trapdoor fractures is of particular importance. This is because early recognition and treatment are necessary to prevent permanent motility abnormities. In this article, we will provide a brief overview of orbital fractures. The clinical and radiographic features of trapdoor fractures will then be reviewed, followed by a discussion on their proper management.

Phan, Laura T.; Jordan Piluek, W.; McCulley, Timothy J.

2012-01-01

111

Orbital Debris Mitigation  

NASA Technical Reports Server (NTRS)

Policies on limiting orbital debris are found throughout the US Government, many foreign space agencies, and as adopted guidelines in the United Nations. The underlying purpose of these policies is to ensure the environment remains safe for the operation of robotic and human spacecraft in near- Earth orbit. For this reason, it is important to consider orbital debris mitigation during the design of all space vehicles. Documenting compliance with the debris mitigation guidelines occurs after the vehicle has already been designed and fabricated for many CubeSats, whereas larger satellites are evaluated throughout the design process. This paper will provide a brief explanation of the US Government Orbital Debris Mitigation Standard Practices, a discussion of international guidelines, as well as NASA's process for compliance evaluation. In addition, it will discuss the educational value of considering orbital debris mitigation requirements as a part of student built satellite design.

Kelley, R. L.; Jarkey, D. R.; Stansbery, G.

2014-01-01

112

Mars Climate Orbiter  

NASA Technical Reports Server (NTRS)

The purpose of this mission is to study the climate history and the water distribution of Mars. Beautiful panoramic views of the shuttle on the launch pad, engine ignition, Rocket launch, and the separation and burnout of the Solid Rocket Boosters are shown. The footage also includes an animation of the mission. Detailed views of the path that the Orbiter traversed were shown. Once the Orbiter lands on the surface of Mars, it will dig a six to eight inch hole and collect samples from the planets' surface. The animation also included the prospective return of the Orbiter to Earth over the desert of Utah. The remote sensor on the Orbiter helps in finding the exact location of the Orbiter so that scientists may collect the sample and analyze it.

1998-01-01

113

Fibrolipoma of the orbit.  

PubMed

Herein we present a retrospective case report of a very rare fibrolipoma originating in the orbit. Lipomas and related variants presenting in the orbit are very rare. Only 2 documented orbital fibrolipomas were noted in our review of literature. A 26-year-old woman presented with a growing mass below the left eyebrow 4 years after suffering facial trauma after being kicked in the face by a horse. CT demonstrated a hypodense nodule adherent to the orbital portion of the left frontal bone that was not encapsulated. An elective left anterior orbitotomy with excisional biopsy was performed, and fibrolipoma was confirmed on histopathologic examination. There was no evidence of tumor after 2-year follow up. The presence of a fibrolipoma in the periosteum of the orbital rim is very rare and might be a result of inflammatory transformation following facial trauma. PMID:23392312

Ali, Sana F; Farber, Martha; Meyer, Dale R

2013-01-01

114

Orbital endoscopic surgery  

PubMed Central

Minimally invasive ?keyhole? surgery performed using endoscopic visualization is increasing in popularity and is being used by almost all surgical subspecialties. Within ophthalmology, however, endoscopic surgery is not commonly performed and there is little literature on the use of the endoscope in orbital surgery. Transorbital use of the endoscope can greatly aid in visualizing orbital roof lesions and minimizing the need for bone removal. The endoscope is also useful during decompression procedures and as a teaching aid to train orbital surgeons. In this article, we review the history of endoscopic orbital surgery and provide an overview of the technique and describe situations where the endoscope can act as a useful adjunct to orbital surgery.

Selva, Dinesh

2008-01-01

115

Visualization of atom's orbits.  

PubMed

High-resolution imaging techniques have been used to obtain views of internal shapes of single atoms or columns of atoms. This review article focuses on the visualization of internal atomic structures such as the configurations of electron orbits confined to atoms. This is accomplished by applying visualization techniques to the reported images of atoms or molecules as well as static and dynamic ions in a plasma. It was found that the photon and electron energies provide macroscopic and microscopic views of the orbit structures of atoms, respectively. The laser-imaged atoms showed a rugged orbit structure, containing alternating dark and bright orbits believed to be the pathways for an externally supplied laser energy and internally excited electron energy, respectively. By contrast, the atoms taken by the electron microscopy provided a structure of fine electron orbits, systematically formed in increasing order of grayscale representing the energy state of an orbit. This structure was identical to those of the plasma ions. The visualized electronic structures played a critical role in clarifying vague postulates made in the Bohr model. Main features proposed in the atomic model are the dynamic orbits absorbing an externally supplied electromagnetic energy, electron emission from them while accompanying light radiation, and frequency of electron waves not light. The light-accompanying electrons and ionic speckles induced by laser light signify that light is composed of electrons and ions. PMID:24749452

Kim, Byungwhan

2014-02-01

116

OL- ORBITAL LIFETIME PROGRAM  

NASA Technical Reports Server (NTRS)

The Orbital Lifetime (OL) program analyzes the long-term motion of Earth-orbiting spacecraft at altitudes of up to 2500 kilometers. It models perturbations to the orbit caused by solar radiation pressure, atmospheric drag, and gravitational effects due to the sun, the moon, and Earth oblateness. OL can be used to predict the orbital lifetime and decay rate of a satellite. The atmospheric density models used in OL are the U.S. Standard Atmosphere for altitudes below 90 km and the Jacchia model for altitudes above 90 km. The Jacchia model requires solar flux and geomagnetic index for the date of orbit. An input file containing these values for 1984 to 1998 is supplied with the OL package. The solar radiation pressure calculations in OL will predict the amount of time a spacecraft is subjected to the Earth's shadow. Input to OL includes spacecraft physical characteristics, initial orbit parameters, and launch date/time. OL calculates time histories of the orbital elements, total lifetime, and decay rates. A spacecraft is considered 'down' at an altitude of 64 km. OL also generates a file of plot data which can be input to a user-supplied graphics program for lifetime plots of altitude against time. OL is written in FORTRAN 77 for interactive or batch execution and has been implemented on a DEC VAX series computer operating under VMS. This program was developed in 1985.

Orr, L. H.

1994-01-01

117

[Orbital fractures in children].  

PubMed

The aim of this article is to review data concerning paediatric orbital fractures. These fractures exhibit strong specificities because they occur in a growing face. Due to the craniofacial growing pattern and the peumatization of paranasal sinuses, there are differences in the anatomical location of orbital fracture with the age: before the age of seven they are mostly orbital roof and after seven they involve the orbital floor. The clinical diagnosis is confirmed with a computed tomography scan (CT scan), gold standard for the imaging in the orbital fractures. The magnetic resonance imaging (MRI) offers a better soft-tissue depiction and is useful when clinical data are not consistent with CT scan findings. The orbital fractures in children are rarely operated. In emergency the main surgical indications are the trap-door fracture involving the ocular muscles and the compressive haematomas. We hypothesize that the periosteum more likely than the bony structure is involved in the responsible trap-door fractures: the thickness and the elasticity of the periosteum leads to reposition the floor or the medial wall of the orbit to its initial position. PMID:21420194

Guyot, L; Lari, N; Benso-Layoun, C; Denis, D; Chossegros, C; Thiery, G

2011-04-01

118

Orbit Stabilization of Nanosat  

SciTech Connect

An algorithm is developed to control a pulsed {Delta}V thruster on a small satellite to allow it to fly in formation with a host satellite undergoing time dependent atmospheric drag deceleration. The algorithm uses four short thrusts per orbit to correct for differences in the average radii of the satellites due to differences in drag and one thrust to symmetrize the orbits. The radial difference between the orbits is the only input to the algorithm. The algorithm automatically stabilizes the orbits after ejection and includes provisions to allow azimuthal positional changes by modifying the drag compensation pulses. The algorithm gives radial and azimuthal deadbands of 50 cm and 3 m for a radial measurement accuracy of {+-} 5 cm and {+-} 60% period variation in the drag coefficient of the host. Approaches to further reduce the deadbands are described. The methodology of establishing a stable orbit after ejection is illustrated in an appendix. The results show the optimum ejection angle to minimize stabilization thrust is upward at 86{sup o} from the orbital velocity. At this angle the stabilization velocity that must be supplied by the thruster is half the ejection velocity. An ejection velocity of 0.02 m/sat 86{sup o} gives an azimuthal separation after ejection and orbit stabilization of 187 m. A description of liquid based gas thrusters suitable for the satellite control is included in an appendix.

JOHNSON,DAVID J.

1999-12-01

119

The Solar Orbiter mission  

NASA Astrophysics Data System (ADS)

Approved in October 2000 by ESA's Science Programme Committee as a flexi-mission, the Solar Orbiter will studythe Sun and unexplored regions of the inner heliosphere from a unique orbit that brings the probe to within 45 solar radii (0.21 AU) of our star, and to solar latitudes as high as 38°. This orbit will allow the Solar Orbiter to make fundamental contributions to our understanding of the acceleration and propagation of energetic particles in the extended solar atmosphere. During quasi-heliosynchronous phases of the orbit, Solar Orbiter will track a given region of the solar surface for several days, making possible unprecedented studies of the sources of impulsive and CME-related particle events. The scientific payload to be carried by the probe will include a sophisticated remote-sensing package, as well as state-of-the-art in-situ instruments. The multi-wavelength, multi-disciplinary approach of Solar Orbiter, combined with its novel location, represents a powerful tool for studies of energetic particle phenomena.

Marsden, R. G.; Fleck, B.

120

The Solar Orbiter mission  

NASA Astrophysics Data System (ADS)

Approved in October 2000 by ESA's Science Programme Committee as a flexi mission, the Solar Orbiter will study the Sun and unexplored regions of the inner heliosphere from a unique orbit that brings the probe to within 45 solar radii (0.21 AU) of our star, and to solar latitudes as high as 38° This orbit will allow the Solar Orbiter to make fundamental contributions to our understanding of the acceleration and propagation of energetic particles in the extended solar atmosphere. During the quasi-heliosynchronous phases of the orbit, Solar Orbiter will track a given region of the solar surface for several days, making possible unprecedented studies of the sources of impulsive and CME-related particle events. The scientific payload to be carried by the probe will include a sophisticated remote-sensing package, as well as state-of-the-art in-situ instruments. The multi-wavelength, multi-disciplinary approach of Solar Orbiter, combined with its novel location, represents a powerful tool for studies of energetic particle phenomena.

Marsden, R.; Fleck, B.

121

Harmonically excited orbital variations  

SciTech Connect

Rephrasing the equations of motion for orbital maneuvers in terms of Lagrangian generalized coordinates instead of Newtonian rectangular cartesian coordinates can make certain harmonic terms in the orbital angular momentum vector more readily apparent. In this formulation the equations of motion adopt the form of a damped harmonic oscillator when torques are applied to the orbit in a variationally prescribed manner. The frequencies of the oscillator equation are in some ways unexpected but can nonetheless be exploited through resonant forcing functions to achieve large secular variations in the orbital elements. Two cases are discussed using a circular orbit as the control case: (1) large changes in orbital inclination achieved by harmonic excitation rather than one impulsive velocity change, and (2) periodic and secular changes to the longitude of the ascending node using both stable and unstable excitation strategies. The implications of these equations are also discussed for both artificial satellites and natural satellites. For the former, two utilitarian orbits are suggested, each exploiting a form of harmonic excitation. 5 refs.

Morgan, T.

1985-08-06

122

External Resource: What is orbit?  

NSDL National Science Digital Library

A 5-8 NASA Education reference answering the question, " What is orbit?" Topics include: satellite, ecliptic plane, perigee, apogee, escape velocity, geosynchronous, polar orbits, and low Earth orbit.

1900-01-01

123

Space Shuttle Orbiter  

NSDL National Science Digital Library

Students learn how orbits are created by a force pulling toward the center in this Moveable Museum unit, in which they build a paper model of a Space Shuttle. This activity simulates an object in orbit. A paper Space Shuttle is swung in a circle on a string. The string provides a pull toward the center of the orbit, simulating the force of gravity. The four-page PDF guide includes suggested background readings for educators, activity notes, and step-by-step directions with suggested discussion questions for older students.

124

Nontraumatic orbital hemorrhage.  

PubMed

Nontraumatic orbital hemorrhage (NTOH) is uncommon. I summarize the published reports of NTOH and offer a classification based on anatomic and etiologic factors. Anatomic patterns of NTOH include diffuse intraorbital hemorrhage, "encysted" hemorrhage (hematic cyst), subperiosteal hemorrhage, hemorrhage in relation to extraocular muscles, and hemorrhage in relation to orbital floor implants. Etiologic factors include vascular malformations and lesions, increased venous pressure, bleeding disorders, infection and inflammation, and neoplastic and nonneoplastic orbital lesions. The majority of NTOH patients can be managed conservatively, but some will have visual compromise and may require operative intervention. Some will suffer permanent visual loss, but a large majority have a good visual outcome. PMID:24359805

McNab, Alan A

2014-01-01

125

The Tajikistan superbolide of July 23, 2008. I. Trajectory, orbit, and preliminary fall data  

NASA Astrophysics Data System (ADS)

The results of the atmospheric trajectory, radiant, heliocentric orbit, and preliminary strewn field calculations for an extremely bright slow-moving fireball are presented. In the evening hours of July 23, 2008, a bright object entered Earth's atmosphere over Tajikistan. The fireball had a -20.3 maximum absolute magnitude and a spectacularly long persistent dust trail remained visible over a widespread region of Tajikistan for about 28 minutes after sunset. The fireball was also recorded by a visible-light satellite system at 14 h 45 min 25 s UT, and the dust trail was imaged by video and photocameras. A unique aspect of this event is that it was detected by two infrasound and five seismic stations too. The bolide was first recorded at a height of 38.2 km, reached its maximum brightness at a height of 35.0 km, and finished at a height of 19.6 km. The first breakup occurred under an aerodynamic pressure of approximately 1.6 MPa, similar to the values derived for breakups of the scarcely reported meteorite-dropping bolides. The fireball's trajectory and dynamic results suggest that meteorite survival is likely. The meteoroid followed an Apollo-like asteroid orbit comparable to those derived for previously recovered meteorites with accurately known orbits.

Konovalova, Natalia A.; Madiedo, Jose M.; Trigo-Rodríguez, Josep M.

2013-12-01

126

Altimetry, Orbits and Tides  

NASA Technical Reports Server (NTRS)

The nature of the orbit error and its effect on the sea surface heights calculated with satellite altimetry are explained. The elementary concepts of celestial mechanics required to follow a general discussion of the problem are included. Consideration of errors in the orbits of satellites with precisely repeating ground tracks (SEASAT, TOPEX, ERS-1, POSEIDON, amongst past and future altimeter satellites) are detailed. The theoretical conclusions are illustrated with the numerical results of computer simulations. The nature of the errors in this type of orbits is such that this error can be filtered out by using height differences along repeating (overlapping) passes. This makes them particularly valuable for the study and monitoring of changes in the sea surface, such as tides. Elements of tidal theory, showing how these principles can be combined with those pertinent to the orbit error to make direct maps of the tides using altimetry are presented.

Colombo, O. L.

1984-01-01

127

Space: Orbiting the Earth  

NSDL National Science Digital Library

In this activity, students solve various problems related to John Glenn's first ride into space, and complete calculations involving velocity, distance and time. Then they calculate the height a satellite would need to be to keep to a geosynchronous orbit.

2010-01-01

128

Spiral Orbit Tribometry, 2.  

National Technical Information Service (NTIS)

The coefficients of friction and relative degradation rates of three lubricants run in the boundary regime in vacuum are evaluated in a Spiral Orbit Tribometer. This tribometer subjected the lubricants to rolling contact conditions similar to those found ...

S. V. Pepper E. P. Kingsbury

2002-01-01

129

Orbiter thermal protection system  

NASA Technical Reports Server (NTRS)

The major material and design challenges associated with the orbiter thermal protection system (TPS), the various TPS materials that are used, the different design approaches associated with each of the materials, and the performance during the flight test program are described. The first five flights of the Orbiter Columbia and the initial flight of the Orbiter Challenger provided the data necessary to verify the TPS thermal performance, structural integrity, and reusability. The flight performance characteristics of each TPS material are discussed, based on postflight inspections and postflight interpretation of the flight instrumentation data. Flights to date indicate that the thermal and structural design requirements for the orbiter TPS are met and that the overall performance is outstanding.

Dotts, R. L.; Curry, D. M.; Tillian, D. J.

1985-01-01

130

Report on orbital debris  

NASA Technical Reports Server (NTRS)

The success of space endeavors depends upon a space environment sufficiently free of debris to enable the safe and dependable operation of spacecraft. An environment overly cluttered with debris would threaten the ability to utilize space for a wide variety of scientific, technological, military, and commercial purposes. Man made space debris (orbital debris) differs from natural meteoroids because it remains in earth orbit during its lifetime and is not transient through the space around the Earth. The orbital debris environment is considered. The space environment is described along with sources of orbital debris. The current national space policy is examined, along with ways to minimize debris generation and ways to survive the debris environment. International efforts, legal issues and commercial regulations are also examined.

1989-01-01

131

Tethered orbital refueling study  

NASA Technical Reports Server (NTRS)

One of the major applications of the space station will be to act as a refueling depot for cryogenic-fueled space-based orbital transfer vehicles (OTV), Earth-storable fueled orbit maneuvering vehicles, and refurbishable satellite spacecraft using hydrazine. One alternative for fuel storage at the space station is a tethered orbital refueling facility (TORF), separated from the space station by a sufficient distance to induce a gravity gradient force that settles the stored fuels. The technical feasibility was examined with the primary focus on the refueling of LO2/LH2 orbital transfer vehicles. Also examined was the tethered facility on the space station. It was compared to a zero-gravity facility. A tethered refueling facility should be considered as a viable alternative to a zero-gravity facility if the zero-gravity fluid transfer technology, such as the propellant management device and no vent fill, proves to be difficult to develop with the required performance.

Fester, Dale A.; Rudolph, L. Kevin; Kiefel, Erlinda R.; Abbott, Peter W.; Grossrode, Pat

1986-01-01

132

Habitability study shuttle orbiter  

NASA Technical Reports Server (NTRS)

Studies of the habitability of the space shuttle orbiter are briefly summarized. Selected illustrations and descriptions are presented for: crew compartment, hygiene facilities, food system and galley, and storage systems.

1972-01-01

133

Spectrophotovoltaic Orbital Power Generation.  

National Technical Information Service (NTIS)

The feasibilty of a spectrophotovoltaic orbital power generation system that optically concentrates solar energy is demonstrated. A dichroic beam-splitting mirror is used to divide the solar spectrum into two wavebands. Absorption of these wavebands by Ga...

J. R. Onffroy

1980-01-01

134

Satellites Orbiting Earth  

NSDL National Science Digital Library

In recent years, there has been a push to better understand how Earth works as a system- how land, oceans, air, and life all interact. Satellites in orbit around Earth are a fast and efficient way of gathering remotely sensed data about the planet as a whole. This animated video shows the orbital paths of the satellites in the National Aeronautics and Space Administration (NASA) Earth Observing System (EOS), a collection of satellites that work together to study Earth on a wide scale.

135

A tapestry of orbits  

SciTech Connect

In this book, the author describes how orbital research developed to yield a rich harvest of knowledge about the earth and its atmosphere. King-Hele relates a personal account of this research based on analysis of satellite orbits between 1957 and 1990 conducted from the Royal Aircraft Establishment in Farnborough England. The early research methods used before the launch of Sputnik in 1957 are discussed.

King-Hele, D.

1992-01-01

136

Two Body Orbits Model  

NSDL National Science Digital Library

The Two Body Orbits model for teachers shows the motion of two objects (binary star or moon-planet system) interacting via Newton's law of universal gravitation. It is designed to teach physics, Earth science, and environmental science topics by showing the spatial path of objects around their common center of mass (barycenter). An optional 3D view shows the celestial sphere and and the orbital plane (ecliptic). Default units are chosen for Earth obit about our Sun so that the distance unit is one astronomical unit and the time unit is one year.   An important feature of the ready-to-run Two Body Orbits simulation is that it can be customized by teachers to meet various learning objectives. The teacher sets the ratio of the two masses, their initial positions and velocities, and various visualization and scale parameters. Documentation, such as an exercise or lesson, can be added to the simulation by entering a filename into the Customization dialog. Selecting the âstudentâ checkbox creates a ready-to-run package with the new configuration without the Customization dialog. The Two Body Orbits model was created using the Easy Java Simulations (EJS) modeling tool. It is distributed as a ready-to-run Java archive. Double clicking the ejs_mech_orbits_TwoBodyOrbits.jar file will run the program if Java is installed. EJS is a part of the Open Source Physics Project and is available in the OSP Collection.

Christian, Wolfgang

2012-07-18

137

Perturbations in orbital elements of a low earth orbiting satellite  

Microsoft Academic Search

The main point of this paper is to evaluate the perturbations in orbital elements of a low Earth orbiting satellite. The outcome of a numerical orbit integration process is the position and velocity vectors of satellite in an inertial coordinate system. The velocity and position vectors are converted into the corresponding orbital elements. Perturbations in a satellite motion affect the

Najafi Alamdari; Nasir Toosi

138

Orbital YORP and asteroid orbit evolution, with application to Apophis  

Microsoft Academic Search

Photon thrust from shape alone can produce quasi-secular changes in an asteroid's orbital elements. An asteroid in an elliptical orbit with a north south shape asymmetry can steadily alter its elements over timescales longer than one orbital trip about the Sun. This thrust, called here orbital YORP (YORP = Yarkovsky O'Keefe Radzievskii Paddack), operates even in the absence of thermal

David Parry Rubincam

2007-01-01

139

Mars Geoscience Orbiter and Lunar Geoscience Orbiter  

NASA Technical Reports Server (NTRS)

The feasibility of using the AE/DE Earth orbiting spacecraft design for the LGO and/or MGO missions was determined. Configurations were developed and subsystems analysis was carried out to optimize the suitability of the spacecraft to the missions. The primary conclusion is that the basic AE/DE spacecraft can readily be applied to the LGO mission with relatively minor, low risk modifications. The MGO mission poses a somewhat more complex problem, primarily due to the overall maneuvering hydrazine budget and power requirements of the sensors and their desired duty cycle. These considerations dictate a modification (scaling up) of the structure to support mission requirements.

Fuldner, W. V.; Kaskiewicz, P. F.

1983-01-01

140

Solar Orbiter --- A High Resolution Mission to the Sun and Inner Heliosphere  

NASA Astrophysics Data System (ADS)

The scientific rationale of the Solar Orbiter (SO) is to provide, at high spatial and temporal resolution, observations of the solar atmosphere and unexplored inner heliosphere. The most interesting and novel observations will be made in the almost heliosynchronous segments of the orbits at heliocentric distances near 45 Rsun and out-of-ecliptic at heliographic latitudes of up to 38o. By going to 45 Rsun the SO will allow remote sensing of the solar atmosphere with unprecedented spatial resolution, and the almost heliosynchronous orbit segments will permit us to disentangle spatial and temporal variations in the solar wind in close linkage with the plasma and radiation conditions in the source regions of the Sun. The strawman payload encompasses two instrument packages: Heliospheric Instruments --- high-res visible light telescope and magnetograph (<40 km), high-res X-ray/EUV imager (<30 km), high-res EUV spectrometer (<100 km), EUV and visible-light coronagraphs, solar neutron and ? -ray detectors, radiometers. Heliospheric Instruments --- solar wind analyzer, magnetometer, energetic particle detectors, IP dust detector, plasma wave analyser, radio experiment, neutral particle detector. Using solar electric propulsion (SEP) in conjunction with multiple planet swing-by manoeuvres, it will take SO two years to reach a perihelion of 45 Rsun at an orbital period of 149 days, with an inclination ranging from 6.7o to 23.4o w.r.t. the ecliptic. During an extended mission phase of about 2 years the inclination will increase to 31.7o, leading to a maximum heliographic latitude of 38.3o. The SO was one of the about 40 responses to the Call for Proposals for the next two "flexi-missions" (F2 and F3) within ESA's Scientific Programme. At its meeting on 1 March 2000, ESA's Space Science Advisory Committee recommended the Solar Orbiter among 5 other proposals for an assessment study. Launch is expected by the end of the decade.

Fleck, B.; Marsch, E.; Schwenn, R.; Antonucci, E.; Bochsler, P.; Bougeret, J.-L.; Harrison, R. A.; Marsden, R.; Vial, J.-C.

2000-05-01

141

Orbital Density Reconstruction for Molecules  

NASA Astrophysics Data System (ADS)

The experimental imaging of electronic orbitals has allowed one to gain a fascinating picture of quantum effects. We here show that the energetically high-lying orbitals that are accessible to experimental visualization in general differ, depending on which approach is used to calculate the orbitals. Therefore, orbital imaging faces the fundamental question of which orbitals are the ones that are visualized. Combining angular-resolved photoemission experiments with first-principles calculations, we show that the orbitals from self-interaction-free Kohn-Sham density functional theory are the ones best suited for the orbital-based interpretation of photoemission.

Dauth, M.; Körzdörfer, T.; Kümmel, S.; Ziroff, J.; Wiessner, M.; Schöll, A.; Reinert, F.; Arita, M.; Shimada, K.

2011-11-01

142

ICESat Precision Orbit Determination  

NASA Astrophysics Data System (ADS)

Following the successful launch of the Ice, Cloud and land Elevation Satellite (ICESat) on January 13, 2003, 00:45 UTC, the GPS receiver on ICESat was turned on successfully on Jan. 17, 2003. High quality GPS data were collected since then to support Precision Orbit Determination (POD) activities. ICESat carries Geoscience Laser Altimeter System (GLAS) to measure ice-sheet topography and associated temporal changes, as well as cloud and atmospheric properties. To accomplish the ICESat science objectives, the position of the GLAS instrument in space should be determined with an accuracy of 5 cm and 20 cm in radial and horizontal components, respectively. This knowledge is acquired by the POD activities using the data collected by the GPS receiver on ICESat and the ground-based satellite laser ranging (SLR) data. It has been shown from pre-launch POD studies that the gravity model error is the dominant source of ICESat orbit errors. The predicted radial orbit errors at the ICESat orbit (600 km altitude) based on pre-launch gravity models, such as TEG-4 and EGM-96, are 7-15 cm. Performance of these gravity models and the recent gravity models from GRACE on ICESat POD were evaluated. The radial orbit accuracy is approaching 1-2 cm level with the GRACE gravity model. This paper also summarizes POD activities at Center for Space Research (CSR), which is responsible to generate ICESat POD products.

Rim, H.; Yoon, S.; Webb, C. E.; Kim, Y.; Schutz, B. E.

2003-12-01

143

Nonmalignant Tumors of the Orbit  

Microsoft Academic Search

\\u000a Most orbital tumors are nonmalignant. Nonmalignant orbital tumors can arise from any of the structures within the orbit, including\\u000a blood vessels, fat, nerves, lacrimal gland, and connective tissue. Nonmalignant orbital tumors can be grouped into cystic\\u000a lesions, vascular tumors, lymphoproliferative lesions, inflammatory lesions, mesenchymal tumors, neurogenic tumors, and lacrimal\\u000a gland tumors. Although most orbital tumors are benign, their location may

Eric M. Hink; Vikram Durairaj

144

Mars Reconnaissance Orbiter Navigation  

NASA Technical Reports Server (NTRS)

Mars Reconnaissance Orbiter will launch in August 2005 at Cape Canaveral Air Force Station. The heavyweight spacecraft will use a Lockheed-Martin Atlas V-401 launch vehicle. It will be the first mission in a low Mars Orbit to characterize the surface, subsurface, and atmospheric properties. The intensive science operation imposes a great challenge for Navigation to satisfy the stringent requirements. This paper describes navigation key requirements, major challenges, and the sophisticated dynamic modeling. It also details navigation strategy and processes for various mission phases. Mars Reconnaissance Orbiter will return significant amount of scientific data in support of the objectives set by the Mars Exploration Program. A robust and precise navigation is the key to the success of this mission.

You, Tung-Han; Halsell, Allen; Highsmith, Dolan; Moriba, Jah; Demcak, Stuart; Higa, Earl; Long, Stacia; Bhaskaran, Shyam

2004-01-01

145

Ballistics and Orbits Model  

NSDL National Science Digital Library

The EJS Ballistics and Orbits model displays ballistic trajectories near the Earth. The model shows the trajectory with respect to the inertial coordinate system and the trajectory as seen from a point of view that is co-rotating with the Earth. You can examine and modify this simulation if you have EJS installed by right-clicking within the plot and selecting âOpen EJS Modelâ from the pop-up menu item. The Ballistics and Orbits model was created using the Easy Java Simulations (EJS) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_nl_teunissen_ballistics_and_orbits.jar file will run the program if Java is installed. Additional information about this model can be found by visiting the authorâs web site: http://www.cleonis.nl/index.htm.

Teunissen, Cleon

2009-11-03

146

Spiral Orbit Tribometer  

NASA Technical Reports Server (NTRS)

The spiral orbit tribometer (SOT) bridges the gap between full-scale life testing and typically unrealistic accelerated life testing of ball-bearing lubricants in conjunction with bearing ball and race materials. The SOT operates under realistic conditions and quickly produces results, thereby providing information that can guide the selection of lubricant, ball, and race materials early in a design process. The SOT is based upon a simplified, retainerless thrust bearing comprising one ball between flat races (see figure). The SOT measures lubricant consumption and degradation rates and friction coefficients in boundary lubricated rolling and pivoting contacts. The ball is pressed between the lower and upper races with a controlled force and the lower plate is rotated. The combination of load and rotation causes the ball to move in a nearly circular orbit that is, more precisely, an opening spiral. The spiral s pitch is directly related to the friction coefficient. At the end of the orbit, the ball contacts the guide plate, restoring the orbit to its original radius. The orbit is repeatable throughout the entire test. A force transducer, mounted in-line with the guide plate, measures the force between the ball and the guide plate, which directly relates to the friction coefficient. The SOT, shown in the figure, can operate in under ultra-high vacuum (10(exp -9) Torr) or in a variety of gases at atmospheric pressure. The load force can be adjusted between 45 and 450 N. By varying the load force and ball diameter, mean Hertzian stresses between 0.5 and 5.0 GPa can be obtained. The ball s orbital speed range is between 1 and 100 rpm.

Pepper, Stephen V.; Jones, William R., Jr.; Kingsbury, Edward; Jansen, Mark J.

2007-01-01

147

Satellite orbit predictor  

NASA Technical Reports Server (NTRS)

An analog aid to determine satellite coverage of Emergency Locator Transmitters Emergency Position Indicating Radio Beacon (ELT/EPIRB) distress incidence is discussed. The satellite orbit predictor is a graphical aid for determining the relationship between the satellite orbit, antenna coverage of the spacecraft and coverage of the Local User Terminal. The predictor allows the user to quickly visualize if a selected position will probably be detected and is composed of a base map and a satellite track overlay for each satellite.A table of equator crossings for each satellite is included.

Friedman, Morton l.; Garrett, James, Major

148

[Orbital arteriovenous anastomoses].  

PubMed

Separate angiography of the channels of a. carotis externa and a. carotis interna revealed two cases with orbital arteriovenous anastomoses between the branches of a. maxillaris interna and v. ophthalmica inferior. In one of these cases the fistule was additionally supplied with blood by branches of a. ophthalmica. The clinical picture of arteriovenous anastomoses of the orbit resembles that of carotid-cavernous fistules. Surgical management consisted in embolization of the channel of a. maxillaris interna on the side of the anastomosis with muscular emboli. The vascular murmur and exophthalmos disappeared after the operation. PMID:716744

Serbinenko, F A; Padalko, P I

1978-01-01

149

Gravity and Orbits  

NSDL National Science Digital Library

The Gravity and Orbits SciPack explores concepts related to Earth's universal gravitation and how gravity affects the universe around us. The focus is on Standards and Benchmarks related to universal gravitation including variables that influence the amount of gravitational force and how gravity governs the motion of the solar system.In addition to comprehensive inquiry-based learning materials tied to Science Education Standards and Benchmarks, the SciPack includes the following additional components:� Pedagogical Implications section addressing common misconceptions, teaching resources and strand maps linking grade band appropriate content to standards. � Access to one-on-one support via e-mail to content "Wizards".� Final Assessment which can be used to certify mastery of the concepts.Learning Outcomes:Gravity and Orbits: Universal Gravitation� Identify gravity as an attractive force associated with all objects, including less intuitive examples (such as soda cans and pencils).� Recognize some examples of phenomena that are the result of Earth's gravity and objects and structures in the universe in general.� Reject the idea that Earth's gravity is an effect of air pushing down toward the surface.� Recognize that gravitational force does not require air (or any other substance) as a medium to act.� Describe gravitational force as a mutual attraction, rather than as one object pulling on another.Gravity and Orbits: Gravitational Force� Identify variables that affect the strength of the gravitational force acting between any two objects.� Provide a quantitative description of the relationship between the mass of two object and the gravitational force between them.� Provide a qualitative description of the relationship between the mass of two objects and the gravitational force between them.� Provide a quantitative description of the relationship between distance and gravitational force. � Provide a qualitative description of the inverse square relationship.� Recognize the effect of air resistance on object falling near Earth's surface, and thus be able to explain why two objects with different masses, at the same distance from Earth's surface, will have equal accelerations if air resistance is ignored. Gravity and Orbits: Orbits� Describe the conditions that would lead an object into orbital motion in terms of the effects of gravitational force.� Explain how an object orbits a planet in terms of trajectories and free fall.� Identify gravity as the force that keeps the planets in their orbits around the Sun and the moons in their orbits around the planets.

National Science Teachers Association (NSTA)

2007-03-21

150

Trajectories and Orbits  

NSDL National Science Digital Library

Materials presented here outline some basic concepts associated with space flight. Users can read about orbits and the difference between an orbit and a trajectory, escape velocities for Earth and some planets, launch velocities and transit times for interplanetary flights, and the effects of time dilation for astronauts travelling at near-light speeds. This is part of the famous Rand corporation study that was commissioned by Congress in 1958 after the Soviet Union stunned the world by launching Sputnik, the world's first artificial satellite.

151

Orbit-orbit interaction and photonic orbital Hall effect in reflection of a light beam  

NASA Astrophysics Data System (ADS)

We examine the orbit—orbit interaction when a paraxial beam with intrinsic orbital angular momentum (IOAM) reflects at an air—glass interface. The orbital-dependent splitting of the beam intensity distribution arises due to the interaction between IOAM and extrinsic orbital angular momentum (EOAM). In addition, we find that the beam centroid shows an orbital-dependent rotation when seen along the propagation axis. However, the motion of the beam centroid related to the orbit—orbit interaction undergoes a straight line trajectory with a small angle inclining from the propagation axis. Similar to a previously developed spin-dependent splitting in the photonic spin Hall effect, the orbital-dependent splitting could lead to the photonic orbital Hall effect.

Zhang, Jin; Zhou, Xin-Xing; Ling, Xiao-Hui; Chen, Shi-Zhen; Luo, Hai-Lu; Wen, Shuang-Chun

2014-06-01

152

Orbital myositis: diagnosis and management.  

PubMed

Orbital myositis is an inflammatory process that primarily involves the extraocular muscles and most commonly affects young adults in the third decade of life, with a female predilection. Clinical characteristics of orbital myositis include orbital and periorbital pain, ocular movement impairment, diplopia, proptosis, swollen eyelids, and conjunctival hyperemia. The most common presentation is acute and unilateral, which initially responds to systemic corticosteroid therapy. However, chronic and recurrent cases may involve both orbits. Many inflammatory, vascular, neoplastic, and infectious conditions that affect the extraocular muscles and other orbital tissue can mimic orbital myositis. The most important differential diagnoses include thyroid-related eye disease, other orbital inflammatory processes (unspecific idiopathic inflammation, vasculitis, and sarcoidosis), orbital cellulitis, and orbital tumors. In refractory, chronic, or recurrent cases, steroid-sparing agents, inmmunosuppressants, or radiation therapy may be indicated. PMID:19656480

Costa, Roberta M S; Dumitrascu, Oana M; Gordon, Lynn K

2009-07-01

153

Mars Climate Orbiter  

NASA Technical Reports Server (NTRS)

The Mars Surveyor '98 Climate Orbiter is shown here during acoustic tests that simulate launch conditions. The orbiter was to conduct a two year primary mission to profile the Martian atmosphere and map the surface. To carry out these scientific objectives, the spacecraft carried a rebuilt version of the pressure modulated infrared radiometer, lost with the Mars Observer spacecraft, and a miniaturized dual camera system the size of a pair of binoculars, provided by Malin Space Science Systems, Inc., San Diego, California. During its primary mission, the orbiter was to monitor Mars atmosphere and surface globally on a daily basis for one Martian year (two Earth years), observing the appearance and movement of atmospheric dust and water vapor, as well as characterizing seasonal changes of the planet's surface. Imaging of the surface morphology would also provide important clues about the planet's climate in its early history. The mission was part of NASA's Mars Surveyor program, a sustained program of robotic exploration of the red planet, managed by the Jet Propulsion Laboratory for NASA's Office of Space Science, Washington, DC. Lockheed Martin Astronautics was NASA's industrial partner in the mission. Unfortunately, Mars Climate Orbiter burned up in the Martian atmosphere on September 23, 1999, due to a metric conversion error that caused the spacecraft to be off course.

1998-01-01

154

Satellite orbits: Plot routines  

NASA Astrophysics Data System (ADS)

Routines for plotting satellite orbits for the Waves in Space Plasmas shuttle-borne experiment are presented. The principles of virtual device coordinate text are outlined. The programs are written in C language on the HP-UX operating system and the Starbase graphics package.

Olsson, Pelle

1987-02-01

155

Global orbit corrections  

SciTech Connect

There are various reasons for preferring local (e.g., three bump) orbit correction methods to global corrections. One is the difficulty of solving the mN equations for the required mN correcting bumps, where N is the number of superperiods and m is the number of bumps per superperiod. The latter is not a valid reason for avoiding global corrections, since, we can take advantage of the superperiod symmetry to reduce the mN simultaneous equations to N separate problems, each involving only m simultaneous equations. Previously, I have shown how to solve the general problem when the machine contains unknown magnet errors of known probability distribution; we made measurements of known precision of the orbit displacements at a set of points, and we wish to apply correcting bumps to minimize the weighted rms orbit deviations. In this report, we will consider two simpler problems, using similar methods. We consider the case when we make M beam position measurements per superperiod, and we wish to apply an equal number M of orbit correcting bumps to reduce the measured position errors to zero. We also consider the problem when the number of correcting bumps is less than the number of measurements, and we wish to minimize the weighted rms position errors. We will see that the latter problem involves solving equations of a different form, but involving the same matrices as the former problem.

Symon, K.

1987-11-01

156

Orbital physics in RIXS  

NASA Astrophysics Data System (ADS)

In contrast to magnetism, phenomena associated with the orbital degrees of freedom in transition metal oxides had always been considered to be very difficult to observe. However, recently resonant inelastic x-ray scattering (RIXS) has established itself as a perfect probe of the orbital excitations [1] and orbital order [2] in transition metal oxides. Here we give a brief overview of these recent theoretical and experimental advances which have inter alia led to the observation of the separation of the spin and orbital degree of freedom of an electron [1, 3].[4pt] [1] J. Schlappa, K. Wohlfeld, K. J. Zhou, M. Mourigal, M. W. Haverkort, V. N. Strocov, L. Hozoi, C. Monney, S. Nishimoto, S. Singh, A. Revcolevschi, J.-S. Caux, L. Patthey, H. M. Rønnow, J. van den Brink, T. Schmitt, Nature 485, 82 (2012).[0pt] [2] P. Marra, K. Wohlfeld, J. van den Brink, Phys. Rev. Lett. 109, 117401 (2012).[0pt] [3] K. Wohlfeld, M. Daghofer, S. Nishimoto, G. Khaliullin, J. van den Brink, Phys. Rev. Lett. 107, 147201 (2011).

Wohlfeld, Krzysztof; Marra, Pasquale; Grueninger, Markus; Schmitt, Thorsten; van den Brink, Jeroen

2013-03-01

157

Orbital Forces: Teacher Page  

NSDL National Science Digital Library

This activity demonstates orbital motions and forces using a tennis ball swung by a ribbon (this activity should be done outside). The Teacher Page contains background information, tennis ball preparation instructions, and wrap up information. This activity is part of Exploring Planets in the Classroom's Planetary Properties series.

158

Orbital Forces: Student Page  

NSDL National Science Digital Library

This activity teaches students about orbital motions and forces using a tennis ball swung by a ribbon. Students answer the question "What happens when you let the ball go?" Background information, activity procedures, and key words are provided. This activity is part of Exploring Planets in the Classroom's Planetary Properties series.

159

Orbit determination: Statistical methods  

Microsoft Academic Search

The problem of finding a satellite trajectory from position and\\/or velocity measurements taken at a given instant in time is examined. A trajectory evolution model including a random vector which represents measurement error is presented. Assuming an iterative approach, the problem is linearized using a previous orbital position estimation. The least squares method is considered in terms of the linear

P. Legendre

1980-01-01

160

Lunar Orbit Anomaly  

NASA Astrophysics Data System (ADS)

Independent experiments show a large anomaly in measurements of lunar orbital evolution, with applications to cosmology and the speed of light. The Moon has long been known to be slowly drifting farther from Earth due to tidal forces. The Lunar Laser Ranging Experiment (LLRE) indicates the Moon's semimajor axis increasing at 3.82 ± .07 cm/yr, anomalously high. If the Moon were today gaining angular momentum at this rate, it would have coincided with Earth less than 2 Gyr ago. Study of tidal rhythmites indicates a rate of 2.9 ± 0.6 cm/yr. Historical eclipse observations independently measure a recession rate of 2.82 ± .08 cm/yr. Detailed numerical simulation of lunar orbital evolution predicts 2.91 cm/yr. LLRE differs from three independent experiments by over12 sigma. A cosmology where speed of light c is related to time t by GM=tc^3 has been suggested to predict the redshifts of Type Ia supernovae, and a 4.507034% proportion of baryonic matter. If c were changing in the amount predicted, lunar orbital distance would appear to increase by an additional 0.935 cm/yr. An anomaly in the lunar orbit may be precisely calculated, shedding light on puzzles of 'dark energy'. In Planck units this cosmology may be summarized as M=R=t.Lunar Recession Rate;

Riofrio, L.

2012-12-01

161

On-orbit refueling  

NASA Technical Reports Server (NTRS)

During the past decade, both NASA and the DOD have conducted numerous space servicing studies. These studies have shown that fluid resupply of on-orbit spacecraft is feasible and would allow for extended spacecraft utilization. In order to prove that the studies have validity, an on-orbit flight demonstration of automatic fluid resupply is required. To embark on this flight demonstration, the system concepts, operational procedures, and conceptual service and target vehicles must be identified. Hernandez Engineering, Inc. (HEI), under the direction of the Space Servicing System Project Office of the NASA/JSC New Initiatives Office, has conducted a systems engineering and integration study. The study objective was to develop preliminary concepts for a flight demonstration of automatic rendezvous, proximity operations, capture, and fluid transfer utilizing servicer and target vehicles. The results show that a servicer vehicle/target kit can be launched to orbit with an ELV and automatically rendezvous and dock with the explorer platform (EP). The servicer vehicle can then separate from the EP/kit, perform proximity maneuvers, redock with the EP/kit, and perform fluid transfer operations. After the on-orbit flight demonstration is completed, the servicer/kit can be separated from the EP and be deorbited into the Earth's atmosphere.

Moore, James S.; Owens, Shelby L.

1993-01-01

162

On-orbit refueling  

NASA Astrophysics Data System (ADS)

During the past decade, both NASA and the DOD have conducted numerous space servicing studies. These studies have shown that fluid resupply of on-orbit spacecraft is feasible and would allow for extended spacecraft utilization. In order to prove that the studies have validity, an on-orbit flight demonstration of automatic fluid resupply is required. To embark on this flight demonstration, the system concepts, operational procedures, and conceptual service and target vehicles must be identified. Hernandez Engineering, Inc. (HEI), under the direction of the Space Servicing System Project Office of the NASA/JSC New Initiatives Office, has conducted a systems engineering and integration study. The study objective was to develop preliminary concepts for a flight demonstration of automatic rendezvous, proximity operations, capture, and fluid transfer utilizing servicer and target vehicles. The results show that a servicer vehicle/target kit can be launched to orbit with an ELV and automatically rendezvous and dock with the explorer platform (EP). The servicer vehicle can then separate from the EP/kit, perform proximity maneuvers, redock with the EP/kit, and perform fluid transfer operations. After the on-orbit flight demonstration is completed, the servicer/kit can be separated from the EP and be deorbited into the Earth's atmosphere.

Moore, James S.; Owens, Shelby L.

1993-02-01

163

A Neptune Orbiter Mission  

NASA Technical Reports Server (NTRS)

This paper describes the results of new analyses and mission/system designs for a low cost Neptune Orbiter mission. Science and measurement objectives, instrumentation, and mission/system design options are described and reflect an aggressive approach to the application of new advanced technologies expected to be available and developed over the next five to ten years.

Wallace, R. A.; Spilker, T. R.

1998-01-01

164

Orbital sonography in children  

Microsoft Academic Search

Orbital sonography with color-flow Doppler imaging is a relatively new technology with significant application in the pediatric patient. This review stresses the primary indications for pediatric ophthalmic ultrasound and also discusses those instances where the use of ultrasound supplements other imaging studies.

F. G. Ramji; T. L. Slovis; J. D. Baker

1996-01-01

165

Space Station: Orbiter Berthing.  

National Technical Information Service (NTIS)

The berthing/docking maneuver is important for the construction and assembly of the Space Station Freedom (SSF). Berthing has a direct effect on the SSF assembly build up and SSF/Orbiter operations. The dynamics associated with the berthing activities pot...

J. Mapar Y. C. Lin M. Kilby

1992-01-01

166

On-orbit refueling  

NASA Astrophysics Data System (ADS)

The goal of this program is to increase operational availability of space assets by refueling with an expendable launch vehicle (not the Shuttle) in LEO or GEO. Information is drawn from the on-orbit refueling model, COSEMS model, COMA study, and information provided from the San Antonio Air Logistics Center.

Pospisil

1993-02-01

167

Apollo Project - Lunar Orbiter  

NASA Technical Reports Server (NTRS)

Lunar Orbiter press conference at the Jet Propulsion Laboratory. A mockup of the solar-powered spacecraft (called the 'Two-Eyed Robot') is shown on the right. It was built by Boeing for the NASA Langley Research Center. From Edgar M. Cortright, 'Scouting the Moon' in Apollo Expeditions to the Moon: 'It was in its photo system that Orbiter was most unconventional. Other spacecraft took TV images and sent them back to Earth as electrical signals. Orbiter took photographs, developed them on board, and then scanned them with a special photoelectric system--a method that, for all its complications and limitations, could produce images of exceptional quality. One Orbiter camera could resolve details as small as 3 feet from an altitude of 30 nautical miles. A sample complication exacted by this performance: because slow film had to be used (because of risk of radiation fogging), slow shutter speeds were also needed. This meant that, to prevent blurring from spacecraft motion, a velocity-height sensor had to insure that the film was moved a tiny, precise, and compensatory amount during the instant of exposure.' Published in Edgar M. Cortright, 'Scouting the Moon, ' in Apollo Expeditions to the Moon, ed. Edgar M. Cortright, (Washington: NASA SP-350, 1975), p. 93.

1966-01-01

168

Interactive Molecular Orbital Diagrams  

NSDL National Science Digital Library

Here is an application for constructing the molecular orbital electron configurations of heteronuclear diatomic molecules. Energy level diagrams are given for the two different cases encountered in heteronuclear diatomics of the first short period (Li2 - Ne2). This is a useful tool for having students explore questions of bond order, magnetic properties and numbers of unpaired electrons.

169

Retinoblastoma associated orbital cellulitis  

PubMed Central

AIM—Preseptal and orbital cellulitis are rare presenting features of intraocular retinoblastoma. The objectives of this study were to determine the frequency of retinoblastoma associated cellulitis, as well as to review its clinical and histopathological features.?METHODS—The medical records of 292 retinoblastoma patients in the King Khaled Eye Specialist Hospital in Riyadh, Saudi Arabia were reviewed. Those indicating a history of, or presenting with, cellulitis were retrieved and their clinical, radiological, and histopathological variables were assessed. Patients with definite extraocular tumour extension on clinical or radiological examination were excluded.?RESULTS—14 patients were found to have retinoblastoma associated cellulitis (4.8%); nine had bilateral and five had unilateral retinoblastoma. Conjunctival and blood cultures were performed in 10 cases and were negative. 10 children were treated with intravenous steroids, often in conjunction with antibiotics, resulting in a prompt decrease in inflammation. Three other children were treated with antibiotics alone and one received no treatment. Computed tomographic scanning depicted large intraocular tumours occupying between 80% and 100% of the globe in each case. In eight patients, periocular inflammation was radiologically interpreted as possible extraocular extension. In one patient serial computed tomographic scanning showed a reduction in intraocular calcification over time which occurred in the presence of cellulitis. 12 patients underwent enucleation and histopathological examination revealed large necrotic, poorly differentiated tumours associated with uveal involvement and early optic nerve invasion. Focal perilimbal destruction was seen in one patient, and in another peripapillary extrascleral extension was present. 12 patients are alive with a mean follow up of 56.4 months.?CONCLUSIONS—Radiological evaluation of scleral integrity may be hindered by periocular inflammatory changes. The orbital cellulitis correlated well with the presence of advanced intraocular retinoblastoma with massive necrosis and anterior chamber involvement. In the majority of patients, cellulitis was not indicative of an extension of retinoblastoma into the orbit. Intravenous steroid treatment reduced orbital inflammation, facilitating examination and subsequent enucleation.?? Keywords: retinoblastoma; orbital cellulitis

Mullaney, P.; Karcioglu, Z.; Huaman, A.; Al-Mesfer, S.

1998-01-01

170

CO-ORBITAL OLIGARCHY  

SciTech Connect

We present a systematic examination of the changes in semimajor axis of a protoplanet as it interacts with other protoplanets in the presence of eccentricity dissipation. For parameters relevant to the oligarchic stage of planet formation, dynamical friction keeps the typical eccentricities small and prevents orbit crossing. Interactions at impact parameters greater than several Hill radii cause the protoplanets to repel each other; if the impact parameter is instead much less than the Hill radius, the protoplanets shift slightly in semimajor axis but remain otherwise unperturbed. If the orbits of two or more protoplanets are separated by less than a Hill radius, they are each pushed toward an equilibrium spacing between their neighbors and can exist as a stable co-orbital system. In the shear-dominated oligarchic phase of planet formation, we show that the feeding zones contain several oligarchs instead of only one. Growth of the protoplanets in the oligarchic phase drives the disk to an equilibrium configuration that depends on the mass ratio of protoplanets to planetesimals, {sigma}/{sigma}. Early in the oligarchic phase, when {sigma}/{sigma} is low, the spacing between rows of co-orbital oligarchs are about 5 Hill radii wide, rather than the 10 Hill radii cited in the literature. It is likely that at the end of oligarchy, the average number of co-orbital oligarchs is greater than unity. In the outer solar system, this raises the disk mass required to form the ice giants. In the inner solar system, this lowers the mass of the final oligarchs and requires more giant impacts than previously estimated. This result provides additional evidence that Mars is not an untouched leftover from the oligarchic phase, but must be composed of several oligarchs assembled through giant impacts.

Collins, Benjamin F.; Sari, Re'em [California Institute of Technology, MC 130-33, Pasadena, CA 91125 (United States)], E-mail: bfc@tapir.caltech.edu

2009-04-15

171

Orbital Fluid Transfer System  

NASA Technical Reports Server (NTRS)

An automated fluid and power interface system needs to be developed for future space missions which require on orbit consumable replenishment. Current method of fluid transfer require manned vehicles and extravehicular activity. Currently the US does not have an automated capability for consumable transfer on-orbit. This technology would benefit both Space Station and long duration satellites. In order to provide this technology the Automated Fluid Interface System (AFIS) was developed. The AFIS project was an advanced development program aimed at developing a prototype satellite servicer for future space operations. This mechanism could transfer propellants, cryogens, fluids, gasses, electrical power, and communications from a tanker unit to the orbiting satellite. The development of this unit was a cooperative effort between Marshall Space Flight Center in Huntsville, Alabama, and Moog, Inc. in East Aurora, New York. An engineering model was built and underwent substantial development testing at Marshall Space Flight Center (MSFC). While the AFIS is not suitable for spaceflight, testing and evaluation of the AFIS provided significant experience which would be beneficial in building a flight unit. The lessons learned from testing the AFIS provided the foundation for the next generation fluid transfer mechanism, the Orbital Fluid Transfer System (OFTS). The OFTS project was a study contract with MSFC and Moog, Inc. The OFTS was designed for the International Space Station (ISS), but its flexible design could used for long duration satellite missions and other applications. The OFTS was designed to be used after docking. The primary function was to transfer bipropellants and high pressure gases. The other items addressed by this task included propellant storage, hardware integration, safety and control system issues. A new concept for high pressure couplings was also developed. The results of the AFIS testing provided an excellent basis for the OFTS design. The OFTS meet the servicing requirements for ISS and could also provide the automated fluid and power interface system needed for on orbit consumable resupply of spacecraft into the new century.

Johnston, A. S., (Nick); Ryder, Mel; Tyler, Tony R.

1998-01-01

172

Single Frequency GPS Orbit Determination for Low Earth Orbiters  

NASA Technical Reports Server (NTRS)

A number of missions in the future are planning to use GPS for precision orbit determination. Cost considerations and receiver availability make single frequency GPS receivers attractive if the orbit accuracy requirements can be met.

Bertiger, Willy; Wu, Sien-Chong

1996-01-01

173

Shuttle on-orbit rendezvous targeting: Circular orbits  

NASA Technical Reports Server (NTRS)

The strategy and logic used in a space shuttle on-orbit rendezvous targeting program are described. The program generates ascent targeting conditions for boost to insertion into an intermediate parking orbit, and generates on-orbit targeting and timeline bases for each maneuver to effect rendezvous with a space station. Time of launch is determined so as to eliminate any plane change, and all work was performed for a near-circular space station orbit.

Bentley, E. L.

1972-01-01

174

Unusual Sclerosing Orbital Pseudotumor Infiltrating Orbits and Maxillofacial Regions  

PubMed Central

Idiopathic orbital pseudotumor (IOP) is a benign inflammatory condition of the orbit without identifiable local or systemic causes. Bilateral massive orbital involvement and extraorbital extension of the IOP is very rare. We present an unusual case of IOP with bilateral massive orbital infiltration extending into maxillofacial regions and discuss its distinctive magnetic resonance imaging (MRI) features that help to exclude other entities during differential diagnoses.

Toprak, Huseyin; Aralasmak, Ayse; Y?lmaz, Temel Fatih; Ozdemir, Huseyin

2014-01-01

175

Orbital YORP and asteroid orbit evolution, with application to Apophis  

Microsoft Academic Search

Photon thrust from shape alone can produce quasi-secular changes in an asteroid's orbital elements. An asteroid in an elliptical orbit with a north–south shape asymmetry can steadily alter its elements over timescales longer than one orbital trip about the Sun. This thrust, called here orbital YORP (YORP = Yarkovsky–O'Keefe–Radzievskii–Paddack), operates even in the absence of thermal inertia, which the Yarkovsky

David Parry Rubincam

2007-01-01

176

Orbit Insertion by Mars Reconnaissance Orbiter (Artist's Concept)  

NASA Technical Reports Server (NTRS)

This is an artist's concept of NASA's Mars Reconnaissance Orbiter during the critical process of Mars orbit insertion. In order to be captured into orbit around Mars, the spacecraft must conduct a 25-minute rocket burn when it is just shy of reaching the planet. As pictured, it will pass under the red planet's southern hemisphere as it begins the insertion burn.

2005-01-01

177

Surgical treatment of orbital cavernomas  

Microsoft Academic Search

BackgroundThere are numerous descriptions for the operative techniques applied in orbital lesions. We present a systematic overview of the surgical approaches, as determined by the location and extension of orbital cavernomas.

Uta Schick; Uwe Dott; Werner Hassler

2003-01-01

178

Measurement of Orbital Volume after Enucleation and Orbital Implantation  

PubMed Central

Introduction This article reports experience relating to the measurement of orbital volume by means of cone beam computed tomography (CBCT) and Cranioviewer program software in patients who have undergone enucleation and orbital implantation. Patients and Methods CBCT scans were made in 30 cases, 10 of which were later excluded because of various technical problems. The study group therefore consisted of 20 patients (8 men and 12 women). The longest follow-up time was 7 years, and the shortest was 1 year. In all 20 cases, the orbital volume was measured with Cranioviewer orbital program software. Slices were made in the ventrodorsal direction at 4.8 mm intervals in the frontal plane, in both bony orbits (both that containing the orbital implant and the healthy one). Similar measurements were made in 20 patients with various dental problems. CBCT scans were recorded for the facial region of the skull, containing the orbital region. The Cranioviewer program can colour the area of the slices red, and it automatically measures the area in mm. Results In 5 of the 20 cases, the first 4 or all 5 slices revealed that the volume of the operated orbit was significantly smaller than that of the healthy orbit, in 12 cases only from 1 to 3 of the slices indicated such a significant difference, and in 3 cases no differences were observed between the orbits. In the control group of patients with various dental problems, there was no significant difference between the two healthy orbits. The accuracy of the volume measurements was assessed statistically by means of the paired samples t-test. Summary To date, no appropriate method is avaliable for exact measurement of the bony orbital volume, which would be of particular importance in orbital injury reconstruction. However, the use of CBCT scans and Cranioviewer orbital program software appears to offer a reliable method for the measurement of changes in orbital volume.

Lukats, Olga; Vizkelety, Tamas; Markella, Zsolt; Maka, Erika; Kiss, Maria; Dobai, Adrienn; Bujtar, Peter; Szucs, Attila; Barabas, Jozsef

2012-01-01

179

Orbital order in vanadium spinels  

Microsoft Academic Search

Motivated by recent theoretical and experimental controversy, we present a theoretical study to clarify the orbital symmetry of the ground state of vanadium spinel oxides AV2O4 ( A=Zn , Mg, Cd). The study is based on an effective Hamiltonian with spin-orbital superexchange interaction and a local spin-orbit coupling term. We construct a classical phase diagram and prove the complex orbital

S. di Matteo; G. Jackeli; N. B. Perkins

2005-01-01

180

Plotting Orbital Trajectories For Maneuvers  

NASA Technical Reports Server (NTRS)

Interactive Orbital Trajectory Planning Tool (EIVAN) computer program is forward-looking interactive orbit-trajectory-plotting software tool for use with proximity operations (operations occurring within 1-km sphere of space station) and other maneuvers. Developed to plot resulting trajectories, to provide better comprehension of effects of orbital mechanics, and to help user develop heuristics for planning missions on orbit. Program runs with Microsoft's Excel for execution on MacIntosh computer running MacIntosh OS.

Brody, Adam R.

1991-01-01

181

Mercury orbiter transport study  

NASA Technical Reports Server (NTRS)

A data base and comparative performance analyses of alternative flight mode options for delivering a range of payload masses to Mercury orbit are provided. Launch opportunities over the period 1980-2000 are considered. Extensive data trades are developed for the ballistic flight mode option utilizing one or more swingbys of Venus. Advanced transport options studied include solar electric propulsion and solar sailing. Results show the significant performance tradeoffs among such key parameters as trip time, payload mass, propulsion system mass, orbit size, launch year sensitivity and relative cost-effectiveness. Handbook-type presentation formats, particularly in the case of ballistic mode data, provide planetary program planners with an easily used source of reference information essential in the preliminary steps of mission selection and planning.

Friedlander, A. L.; Feingold, H.

1977-01-01

182

Uprated orbital maneuvering engine  

NASA Technical Reports Server (NTRS)

The baseline orbital maneuvering system (OMS) of the Space Shuttle has the potential for significant performance uprating, leading to increased Shuttle payload capability. The baseline OMS, its requirements, and its operational characteristics are described. Potential uprating approaches are discussed and the logic for selection of a higher performance engine is presented. It is shown that a higher performance engine essentially means an engine operating at higher pressures and that a pump-fed engine is necessary for the higher pressure operation. A description of the uprated OMS engine, including requirements, baseline engine characteristics, and significant engine issues, is presented. Discussion of the program underway at the NASA Lyndon B. Johnson Space Center to attain additional insight into these issues, through the performance of a component demonstration program, includes the technical objectives, approach, and program schedule. The plans for further development are presented, culminating in the plans for integration with the Orbiter and the Shuttle system.

Hooper, J. C.

1984-01-01

183

Orbital and intraocular myofibroblastoma.  

PubMed

Abstract A 66-year-old woman presented with a blind, painful, hypertensive, and proptotic left eye. Computed tomographic imaging revealed a well-circumscribed mass involving the left orbit and globe. Metastatic work-up failed to reveal extraorbital lesions and the tumor was removed in toto via an evisceration approach orbitotomy. Histopathology and immunohistochemistry were most consistent with mammary-type myofibroblastoma with fascicles of bland, uniform spindle cells that stained positive for desmin and CD34. We are not aware of previous reports of orbital or ocular myofibroblastoma. This neoplasm has not been shown to recur, undergo malignant transformation, or metastasize. Familiarity with its clinical, histopathologic, and immunohistochemical features may improve diagnostic accuracy and treatment decisions for patients presenting with similar findings. PMID:24410721

Costin, Bryan R; Plesec, Thomas P; Rubinstein, Tal J; Medina, Carlos A; Singh, Arun D; Goldblum, John R; Perry, Julian D

2014-06-01

184

Lunar Reconnaissance Orbiter  

NSDL National Science Digital Library

Humans have been to the moon numerous times, but the United States is gearing up to do so again with the creation of the Lunar Reconnaissance Orbiter (LRO) mission. With a launch date of October 31, 2008, the goal of the LRO is to obtain "data that will facilitate returning humans safely to the Moon and enable extended stays.ïÿý On this site, visitors can learn all of the excellent details about the mission. The site includes a timeline of scheduled events, the particulars about the spacecraft and its instruments, and a wide range of multimedia files and images. In keeping with NASA's high video standards, there are a number of rather remarkable short films here, including one that shows the LRO orbiting the moon.

185

Solitary orbital cysticercosis  

Microsoft Academic Search

Isolated orbital cysticercosis is rare. A 54-year-old woman had unilateral, painful, axial, and downward proptosis; palpable,\\u000a superomedial mass; blepharoptosis; and painful ocular movements. Findings of ultrasonography and computed tomography corroborated\\u000a the clinical diagnosis of pseudotumor. However, failure of medical therapy prompted us to order magnetic resonance imaging\\u000a (MRI), which outlined a cyst with cysticercus features. Death of the parasite was

Usha Yadava; Punita Kumari Sodhi

2000-01-01

186

Developing Lunar Orbiter  

Microsoft Academic Search

In January 1961 the Hughes Aircraft Company was selected to build the Surveyor spacecraft. With a planned mass of about 1,125\\u000a kg at translunar injection, it would require the Atlas-Centaur. The plan was for the orbital version to provide wide-area\\u000a mapping and reconnaissance of potential landing sites for the surface Surveyors and, later, for Apollo. The mass at touchdown\\u000a was

David M. Harland

187

Solar sail orbit operations  

Microsoft Academic Search

The inherent capabilities of solar sails and the fact that they need no onboard supplies of fuel for propulsion make them well suited for use in long-term, multiple-objective missions. They are especially well suited for the exploration of asteroids. In this dissertation, both hovering points and orbiting trajectories about point-mass asteroids using equations of motion for a perfectly reflecting solar

Esther Marie Morrow

2002-01-01

188

Spectrophotovoltaic orbital power generation  

NASA Technical Reports Server (NTRS)

The feasibilty of a spectrophotovoltaic orbital power generation system that optically concentrates solar energy is demonstrated. A dichroic beam-splitting mirror is used to divide the solar spectrum into two wavebands. Absorption of these wavebands by GaAs and Si solar cell arrays with matched energy bandgaps increases the cell efficiency while decreasing the amount of heat that must be rejected. The projected cost per peak watt if this system is $2.50/W sub p.

Onffroy, J. R.

1980-01-01

189

Small Mercury Relativity Orbiter  

NASA Technical Reports Server (NTRS)

The accuracy of solar system tests of gravitational theory could be very much improved by range and Doppler measurements to a Small Mercury Relativity Orbiter. A nearly circular orbit at roughly 2400 km altitude is assumed in order to minimize problems with orbit determination and thermal radiation from the surface. The spacecraft is spin-stabilized and has a 30 cm diameter de-spun antenna. With K-band and X-band ranging systems using a 50 MHz offset sidetone at K-band, a range accuracy of 3 cm appears to be realistically achievable. The estimated spacecraft mass is 50 kg. A consider-covariance analysis was performed to determine how well the Earth-Mercury distance as a function of time could be determined with such a Relativity Orbiter. The minimum data set is assumed to be 40 independent 8-hour arcs of tracking data at selected times during a two year period. The gravity field of Mercury up through degree and order 10 is solved for, along with the initial conditions for each arc and the Earth-Mercury distance at the center of each arc. The considered parameters include the gravity field parameters of degree 11 and 12 plus the tracking station coordinates, the tropospheric delay, and two parameters in a crude radiation pressure model. The conclusion is that the Earth-Mercury distance can be determined to 6 cm accuracy or better. From a modified worst-case analysis, this would lead to roughly 2 orders of magnitude improvement in the knowledge of the precession of perihelion, the relativistic time delay, and the possible change in the gravitational constant with time.

Bender, Peter L.; Vincent, Mark A.

1989-01-01

190

[Echinococcosis of the orbit].  

PubMed

A 5 year old girl with an echinococcuscyst in the right orbit is reported. The final diagnosis was made by removal of the cyst. A second cyst was found in the liver. The epidemiology, clinical and diagnostic problems of echinococcosis are reviewed. Radical surgery is still the only reliable treatment. For inoperable cases chemotherapy with Mebendazol seems promising. Many problems of chemotherapy remain to be solved and Mebendazol therapy is still in an experimental stage. PMID:4077595

Staindl, O; Krenkel, C

1985-09-01

191

Interplanetary orbit determination  

NASA Technical Reports Server (NTRS)

The logistical aspects of orbit determination (OD) in the interplanetary phase of the Mariner Mars 1971 mission are described and the working arrangements for the OD personnel, both within the Navigation Team and with outside groups are given. Various types of data used in the OD process are presented along with sources of the data. Functional descriptions of the individual elements of the OD software and brief sketches of their modes of operation are provided.

Zielenbach, J. W.; Acton, C. H.; Born, G. H.; Breckenridge, W. G.; Chao, C. C.; Duxbury, T. C.; Green, D. W.; Jerath, N.; Jordan, J. F.; Mottinger, N. A.

1973-01-01

192

An Orbit Plan toward AKATSUKI Venus Reencounter and Orbit Injection  

NASA Technical Reports Server (NTRS)

On December 7, 2010, AKATSUKI, the Japanese Venus explorer reached its destination and tried to inject itself into Venus orbit. However, due to a malfunction of the propulsion system, the maneuver was interrupted and AKATSUKI again escaped out from the Venus into an interplanetary orbit. Telemetry data from AKATSUKI suggests the possibility to perform orbit maneuvers to reencounter the Venus and retry Venus orbit injection. Reported in this paper is an orbit plan investigated under this situation. The latest results reflecting the maneuvers conducted in the autumn 2011 is introduced as well.

Kawakatsu, Yasuhiro; Campagnola, Stefano; Hirose, Chikako; Ishii, Nobuaki

2012-01-01

193

Exenteration for benign orbital disease  

Microsoft Academic Search

Exenteration, or removal of the globe with part or all of the surrounding orbital contents, is generally reserved for malignancy. The procedure may, however, be of value in the management of some benign orbital diseases. The indications for exenteration in management of benign orbital disease are threefold. Firstly, patients in whom diffuse disease, such as idiopathic inflammation, has resulted in

G E Rose; J E Wright

1994-01-01

194

Orbital order driven quantum criticality  

Microsoft Academic Search

Charge, spin, and orbital degrees of freedom underlie the physics of transition metal compounds. Much work has revealed quantum critical points associated with spin and charge degrees of freedom in many of these systems. Here we illustrate that the simplest models that embody the orbital degrees of freedom ---the two- and three-dimensional quantum orbital compass models--- exhibit an exact quantum

Zohar Nussinov; Gerardo Ortiz

2008-01-01

195

Heteronuclear Diatomic Molecular Orbital Formation  

NSDL National Science Digital Library

Here is a set of movies that demonstrates heteronuclear diatomic molecular orbital formation. The orbitals start at a distance where there is little or no interatomic interaction and move to the appropriate bond distance. Orbital phase is shown by the different colors.

196

Orbiter Autoland reliability analysis  

NASA Technical Reports Server (NTRS)

The Space Shuttle Orbiter is the only space reentry vehicle in which the crew is seated upright. This position presents some physiological effects requiring countermeasures to prevent a crewmember from becoming incapacitated. This also introduces a potential need for automated vehicle landing capability. Autoland is a primary procedure that was identified as a requirement for landing following and extended duration orbiter mission. This report documents the results of the reliability analysis performed on the hardware required for an automated landing. A reliability block diagram was used to evaluate system reliability. The analysis considers the manual and automated landing modes currently available on the Orbiter. (Autoland is presently a backup system only.) Results of this study indicate a +/- 36 percent probability of successfully extending a nominal mission to 30 days. Enough variations were evaluated to verify that the reliability could be altered with missions planning and procedures. If the crew is modeled as being fully capable after 30 days, the probability of a successful manual landing is comparable to that of Autoland because much of the hardware is used for both manual and automated landing modes. The analysis indicates that the reliability for the manual mode is limited by the hardware and depends greatly on crew capability. Crew capability for a successful landing after 30 days has not been determined yet.

Welch, D. Phillip

1993-01-01

197

Global Orbit Feedback in RHIC  

SciTech Connect

For improved reproducibility of good operating conditions and ramp commissioning efficiency, new dual-plane slow orbit feedback during the energy ramp was implemented during run-10 in the Relativistic Heavy Ion Collider (RHIC). The orbit feedback is based on steering the measured orbit, after subtraction of the dispersive component, to either a design orbit or to a previously saved reference orbit. Using multiple correctors and beam position monitors, an SVD-based algorithm is used for determination of the applied corrections. The online model is used as a basis for matrix computations. In this report we describe the feedback design, review the changes made to realize its implementation, and assess system performance.

Minty, M.; Hulsart, R.; Marusic, A.; Michnoff, R.; Ptitsyn, V.; Robert-Demolaize, G.; Satogata, T.

2010-05-23

198

Lunar Prospector Orbit Determination Results  

NASA Technical Reports Server (NTRS)

The orbit support for Lunar Prospector (LP) consists of three main areas: (1) cislunar orbit determination, (2) rapid maneuver assessment using Doppler residuals, and (3) routine mapping orbit determination. The cislunar phase consisted of two trajectory correction maneuvers during the translunar cruise followed by three lunar orbit insertion burns. This paper will detail the cislunar orbit determination accuracy and the real-time assessment of the cislunar trajectory correction and lunar orbit insertion maneuvers. The non-spherical gravity model of the Moon is the primary influence on the mapping orbit determination accuracy. During the first two months of the mission, the GLGM-2 lunar potential model was used. After one month in the mapping orbit, a new potential model was developed that incorporated LP Doppler data. This paper will compare and contrast the mapping orbit determination accuracy using these two models. LP orbit support also includes a new enhancement - a web page to disseminate all definitive and predictive trajectory and mission planning information. The web site provides definitive mapping orbit ephemerides including moon latitude and longitude, and four week predictive products including: ephemeris, moon latitude/longitude, earth shadow, moon shadow, and ground station view periods. This paper will discuss the specifics of this web site.

Beckman, Mark; Concha, Marco

1998-01-01

199

Orbital Debris: A Policy Perspective  

NASA Technical Reports Server (NTRS)

A viewgraph presentation describing orbital debris from a policy perspective is shown. The contents include: 1) Voyage through near-Earth Space-animation; 2) What is Orbital Debris?; 3) Orbital Debris Detectors and Damage Potential; 4) Hubble Space Telescope; 5) Mir Space Station Solar Array; 6) International Space Station; 7) Space Shuttle; 8) Satellite Explosions; 9) Satellite Collisions; 10) NASA Orbital Debris Mitigation Guidelines; 11) International Space Station Jettison Policy; 12) Controlled/Uncontrolled Satellite Reentries; 13) Return of Space Objects; 14) Orbital Debris and U.S. National Space Policy; 15) U.S Government Policy Strategy; 16) Bankruptcy of the Iridium Satellite System; 17) Inter-Agency Space Debris Coordination Committee (IADC); 18) Orbital Debris at the United Nations; 19) Chinese Anti-satellite System; 20) Future Evolution of Satellite Population; and 21) Challenge of Orbital Debris

Johnson, Nicholas L.

2007-01-01

200

Orbit synthesis for target satellites  

NASA Astrophysics Data System (ADS)

The purpose of the study is to illustrate the orbit synthesis process for a hypothetical test of a direct-ascent-based kinetic energy weapon (KEW) against an instrumented test vehicle. Test arena and communications considerations for a ground-based directed energy weapon and a direct-ascent-based KEW are outlined, along with launch vehicle constraints, algorithms for off-nominal orbits, and thermal-control and orbit lifetime considerations. Focus is placed on altitude and illumination cycles, general-test and detailed-test constraints, and methodologies for assessing orbit performance. The orbit synthesis is demonstratedd, with emphasis on the test opportunity influence on orbit inclination, test window concept, selection of apogee altitude, orbit inclination, perigee altitude, launch window, and the effect of the launch date.

Wilkinson, Charles K.

201

Orbiter door closure tools  

NASA Technical Reports Server (NTRS)

Safe reentry of the shuttle orbiter requires that the payload bay doors be closed and securely latched. Since a malfunction in the door drive or bulkhead latch systems could make safe reentry impossible, the requirement to provide tools to manually close and secure the doors was implemented. The tools would disconnect a disabled door or latch closure system and close and secure the doors if the normal system failed. The tools required to perform these tasks have evolved into a set that consists of a tubing cutter, a winch, a latching tool, and a bolt extractor. The design, fabrication, and performance tests of each tool are described.

Acres, W. R.

1980-01-01

202

Weather Satellite and Orbits  

NSDL National Science Digital Library

In this interactive, online module, students learn about satellite orbits (geostationary and polar), remote-sensing satellite instruments (radiometers and sounders), satellite images, and the math and physics behind satellite technology. The module is part of an online course for grades 7-12 in satellite meteorology, which includes 10 interactive modules. The site also includes lesson plans developed by teachers and links to related resources. Each module is designed to serve as a stand-alone lesson, however, a sequential approach is recommended. Designed to challenge students through the end of 12th grade, middle school teachers and students may choose to skim or skip a few sections.

203

[Porous orbital implants].  

PubMed

Since the introduction of the first coralline hydroxyapatite porous orbital implant as eye replacement in the early 1980s, numerous other modified porous implants have been developed. Due to the different design of the existing studies concerning long-term safety with, in some cases, relatively short follow-up, a comparison is difficult and none of the implant types can be clearly identified as being superior. Factors affecting the exposure rate of the implant seem to be the implant coating, the surgical technique and the condition of the patient's tissue at the beginning of surgery. PMID:24942122

Cleres, B; Meyer-Rüsenberg, H W

2014-06-01

204

Cryogen acquisition in orbit  

NASA Technical Reports Server (NTRS)

Orbital cryogen acquisition is a definite requirement for engine restart and/or propellant transfer on all major future missions. The most promising methods, especially for large scale vehicles, are acquisition by linear acceleration and acquisition by capillary systems. Intermittent acceleration and propellant settling requires some state-of-the-art extension since it has not been attempted on a large scale cryogen vehicle. Capillary acquisition systems offer the advantages of reusability, passiveness, low weight, and mission flexibility. The major disadvantage is that of an undeveloped technology. The method does not lend itself to verification through ground testing.

Hastings, L. J.

1971-01-01

205

The Earth's Orbit  

NSDL National Science Digital Library

These eleven activities relate to the results of the motion and position of the Earth in its orbit, investigating both the causes and the effects of changing seasons. It starts simply by trying to quantify the observation that it is colder in the winter and ends by measuring the tilt of the Earth. This is chapter two of the online book Eyes on the Sky, Feet on the Ground, containing explorations into astronomy as a classroom tool for learning how to theorize, experiment, and analyze data. The activities are fully illustrated and contain detailed, step-by-step instructions as well as suggested discussion topics.

2007-12-12

206

Lunar Exploration Orbiter (LEO)  

NASA Astrophysics Data System (ADS)

The Moon is an integral part of the Earth-Moon system, it is a witness to more than 4.5 b. y. of solar system history, and it is the only planetary body except Earth for which we have samples from known locations. The Moon is our closest companion and can easily be reached from Earth at any time, even with a relatively modest financial budget. Consequently, the Moon was the first logical step in the exploration of our solar system before we pursued more distant targets such as Mars and beyond. The vast amount of knowledge gained from the Apollo and other lunar missions of the late 1960's and early 1970's demonstrates how valuable the Moon is for the understanding of our planetary system. Even today, the Moon remains an extremely interesting target scientifically and technologically, as ever since, new data have helped to address some of our questions about the Earth-Moon system, many questions remained. Therefore, returning to the Moon is the critical stepping-stone to further exploring our immediate planetary neighborhood. In this concept study, we present scientific and technological arguments for a national German lunar mission, the Lunar Explorations Orbiter (LEO). Numerous space-faring nations have realized and identified the unique opportunities related to lunar exploration and have planned missions to the Moon within the next few years. Among these missions, LEO will be unique, because it will globally explore the Moon in unprecedented spatial and spectral resolution. LEO will significantly improve our understanding of the lunar surface composition, surface ages, mineralogy, physical properties, interior, thermal history, gravity field, regolith structure, and magnetic field. The Lunar Explorations Orbiter will carry an entire suite of innovative, complementary technologies, including high-resolution camera systems, several spectrometers that cover previously unexplored parts of the electromagnetic spectrum over a broad range of wavelengths, microwave and radar experiments, a very sensitive magnetometer and gradiometer, a subsatellite, and a state-of-the-art optical communication system. The Lunar Explorations Orbiter concept is technologically challenging but feasible, and will gather unique, integrated, interdisciplinary data sets that are of high scientific interest and will provide an unprecedented new context for all other international lunar missions. In fact, the Lunar Explorations Orbiter will further establish Germany as a leader among space-faring nations and will demonstrate expertise and technological know-how, which is "Made in Germany". With its high visibility, LEO will foster the growing acceptance of space exploration in Germany and will capture the imagination of the general public.

Jaumann, R.; Spohn, T.; Hiesinger, H.; Jessberger, E. K.; Neukum, G.; Oberst, J.; Helbert, J.; Christensen, U.; Keller, H. U.; Mall, U.; Böhnhardt, H.; Hartogh, P.; Glassmeier, K.-H.; Auster, H.-U.; Moreira, A.; Werner, M.; Pätzold, M.; Palme, H.; Wimmer-Schweingruber, R.; Mandea, M.; Lesur, V.; Häusler, B.; Hördt, A.; Eichentopf, K.; Hauber, E.; Hoffmann, H.; Köhler, U.; Kührt, E.; Michaelis, H.; Pauer, M.; Sohl, F.; Denk, T.; van Gasselt, S.

2007-08-01

207

Counter-Orbitals: Another Class of Co-Orbitals  

NASA Astrophysics Data System (ADS)

Co-orbital companions share the same orbital period and semi-major axis about a primary (star or planet). Heretofore there have been three recognized classes of co-orbitals: (1) Trojans librate in tadpole-shaped orbits about the equilateral Lagrange points L4 and L5, 60 degrees ahead of or behind the secondary (planet or satellite). (2) Horse-shoe companions librate about both L4 and L5, as well as the L3 Lagrange point diametrically opposite the secondary. (3) ``Quasi-satellites'' appear to be in distant retrograde orbits about the secondary, but actually are in prograde orbits about the primary with the same period as the secondary. Quasi-satellite orbits lie outside the secondary's Hill sphere, and enclose both L1 and L2, and sometimes L4 and L5 as well. In addition, some asteroids and comets are found in hybrid orbits which alternate among the above three classes, or combine some of their features. New research now reveals a fourth class of co-orbitals, which does not appear to be known before, and may be called ``counter-orbitals''. Imagine reversing the inertial velocity of a distant quasi-satellite. Then it remains in orbit about the primary, with the same period, semi-major axis, eccentricity, and orbital plane, although retrograde. But instead of remaining relatively close to the secondary, now it passes the secondary twice per orbit, near periapsis and apoapsis. The attractive impulses at these conjunctions tend to stabilize this arrangement. Numerical simulations of the general three-body problem verify that counter-orbitals can persist for over 10,000 orbits, with small vertical excursions, but a wide range of eccentricities and mass ratios. For example, Charon can maintain counter-orbital companions at least up to 3 percent of its own mass, in eccentric orbits extending from about 7050 km out to 41700 km from the center of Pluto. This may present a collision hazard to the New Horizons spacecraft.

Dobrovolskis, Anthony R.

2012-10-01

208

Periodic orbits for three and four co-orbital bodies  

NASA Astrophysics Data System (ADS)

We investigate the natural families of periodic orbits associated with the equilibrium configurations of the planar-restricted 1 + n-body problem for the case 2 ? n ? 4 equal-mass satellites. Such periodic orbits can be used to model both trojan exoplanetary systems and parking orbits for captured asteroids within the Solar system. For n = 2, there are two families of periodic orbits associated with the equilibria of the system: the well-known horseshoe and tadpole orbits. For n = 3, there are three families that emanate from the equilibrium configurations of the satellites, while for n = 4, there are six such families as well as numerous additional connecting families. The families of periodic orbits are all of the horseshoe or tadpole type, and several have regions of neutral linear stability.

Verrier, P. E.; McInnes, C. R.

2014-08-01

209

Microdebrider use in orbital surgery.  

PubMed

Abstract Purpose: To report the novel use of a sinus microdebrider for the removal of tissue during orbital surgery. Methods: This retrospective study reviewed the logs of 3 surgeons to identify patients who required orbital surgery during which the surgeon chose to use a sinus microdebrider with an open sky technique as a means of removing portions of the orbital tissue. Collected data included patient demographics, clinical examinations, pathologic diagnoses, radiologic studies, operative reports and, when available, photographs and intra-operative video. Results: Three patients were identified as having undergone orbital surgery assisted by the use of a sinus microdebrider. The first patient had an extensive, recurrent left orbital myxoid tumor. Debulking of this gelatinous, infiltrative mass was aided by the combined suction and cutting action of the microdebrider. Two cases involved orbital exenteration for infiltrative sino-orbital fungus infection resulting in a blind eye and frozen globe. Removal of orbital apical tissue during exenteration surgery was facilitated with the microdebrider. Conclusions: The characteristics of the sinus microdebrider make it a useful adjunct for orbital surgery, particularly in situations where tissue may be difficult to grasp and excise. Caution should be exercised whenever using this electrically powered tool due to its potential for rapid tissue destruction. Therefore, the microdebrider should only be used in cases in which there is little risk of damage to essential orbital structures. PMID:24678870

Freitag, Suzanne K; Yoon, Michael K; Callahan, Alison B; Lee, N Grace; Lefebvre, Daniel R

2014-06-01

210

Orbital YORP and asteroid orbit evolution, with application to Apophis  

NASA Astrophysics Data System (ADS)

Photon thrust from shape alone can produce quasi-secular changes in an asteroid's orbital elements. An asteroid in an elliptical orbit with a north-south shape asymmetry can steadily alter its elements over timescales longer than one orbital trip about the Sun. This thrust, called here orbital YORP (YORP = Yarkovsky-O'Keefe-Radzievskii-Paddack), operates even in the absence of thermal inertia, which the Yarkovsky effects require. However, unlike the Yarkovsky effects, which produce secular orbital changes over millions or billions of years, the change in an asteroid's orbital elements from orbital YORP operates only over the precession timescale of the orbit or of the asteroid's spin axis; this is generally only thousands or tens of thousands of years. Thus while the orbital YORP timescale is too short for an asteroid to secularly journey very far, it is long enough to warrant investigation with respect to 99942 Apophis, which might conceivably impact the Earth in 2036. A near-maximal orbital YORP effect is found by assuming Apophis is without thermal inertia and is shaped like a hemisphere, with its spin axis lying in the orbital plane. With these assumptions orbital YORP can change its along-track position by up to ±245 km, which is comparable to Yarkovsky effects. Though Apophis' shape, thermal properties, and spin axis orientation are currently unknown, the practical upper and lower limits are liable to be much less than the ±245 km extremes. Even so, the uncertainty in position is still likely to be much larger than the ˜0.5 km "keyhole" Apophis must pass through during its close approach in 2029 in order to strike the Earth in 2036.

Rubincam, David Parry

2007-12-01

211

Orbital debris issues  

NASA Astrophysics Data System (ADS)

Orbital debris issues fall into three major topics: Environment Definition, Spacecraft Hazard, and Space Object Management. The major issue under Environment Definition is defining the debris flux for sizes smaller (10 cm in diameter) than those tracked by the North American Aerospace Defense Command (NORAD). Sources for this size debris are fragmentation of larger objects, either by explosion or collision, and solid rocket motor products. Modeling of these sources can predict fluxes in low Earth orbit which are greater than the meteoroid environment. Techniques to measure the environment in the size interval between 1 mm and 10 cm are being developed, including the use of telescopes and radar both on the ground and in space. Some impact sensors designed to detect meteoroids may have detected solid rocket motor products. Once the environment is defined, it can be combined with hypervelocity impact data and damage criteria to evaluate the Spacecraft Hazard. Shielding may be required to obtain an acceptable damage level. Space Object Management includes techniques to control the environment and the desired policy to effectively minimize the hazard to spacecraft. One control technique - reducing the likelihood of future explosions in space - has already been implemented by NASA. The effectiveness of other techniques has yet to be evaluated.

Kessler, D. J.

212

Observed Orbital Eccentricities  

NASA Astrophysics Data System (ADS)

For binaries with periods of more than a few weeks, nearly all eccentricities from zero (circular) to nearly one (highly elliptical) are possible. What are the average characteristics and limiting values? I considered the 1169 spectroscopic and visual systems with known orbital elements and B0-M5 dwarf primaries. The average eccentricities as a function of orbital period show a very systematic behavior. For systems with periods greater than about 1000 days, all eccentricities are equally probable, showing that in the process of binary formation, no specific eccentricities are favored. It is well known that for periods of a few days, all systems have been circularized by tidal interactions. For periods between a few days and 1000 days, the mean eccentricities increase from zero to a mean asymptotic value of 0.5. The upper limiting eccentricities are 0.8 for periods of months, 0.7 for periods of weeks, and 0.3 for periods around one week. Double-lined binaries tend to have higher mean eccentricities than single-lined ones of the same periods in accord with Kepler's third law because they have greater total masses and hence larger separations. Systems with giant primaries have the same behavior except they are circularized for periods less than about 70 days.

Abt, Helmut A.

2007-08-01

213

Orbital construction demonstration study  

NASA Technical Reports Server (NTRS)

A conceptual design and program plan for an Orbital Construction Demonstration Article (OCDA) was developed that can be used for evaluating and establishing practical large structural assembly operations. A flight plan for initial placement and continued utility is presented as a basic for an entirely new shuttle payload line-item having great future potential benefit for space applications. The OCDA is a three-axis stabilized platform in low-earth orbit with many structural nodals for mounting large construction and fabrication equipments. This equipment would be used to explore methods for constructing the large structures for future missions. The OCDA would be supported at regular intervals by the shuttle. Construction experiments and consumables resupply are performed during shuttle visit periods. A 250 kw solar array provides sufficient power to support the shuttle while attached to the OCDA and to run construction experiments at the same time. Wide band communications with a Telemetry and Data Relay Satellite compatible high gain antenna can be used between shuttle revisits to perform remote controlled, TV assisted construction experiments.

1976-01-01

214

Finite thrust orbital transfers  

NASA Astrophysics Data System (ADS)

The finite thrust optimal transfer in the presence of the Earth?s shadow and oblate planet perturbations is a problem of strong interest in modern telecommunication satellite design with plasmic propulsion. The Maximum Principle cannot be used in its standard form to deal with the Earth?s shadow. In this paper, using a regularization of the Hamiltonian which expands the Maximum Principle application domain, we provide for the first time, the necessary conditions in a very general context for the finite thrust optimal transfer with limited power around an oblate planet. The costate in such problems is generally discontinuous. To obtain fast numerical solutions, the averaging of the Hamiltonian is introduced. Two classes of boundary conditions are analyzed and numerically solved: the minimum time and the minimum fuel at a fixed time. These two problems are the basic tools for designing the orbit raising of a satellite after the launcher injection into its separation orbit. Numerical solutions have been calculated for the more important applications of LEO to GEO/MEO missions and the results have been reported and discussed.

Mazzini, Leonardo

2014-07-01

215

The orbital surgeon.  

PubMed Central

While the number of orbital surgeons is limited, it is hoped these can be recognized and patients referred to them by ophthalmologists not interested or trained in that specialty. Let the orbital surgeon determine whether he can handle the problem in 1 to 2 days, or whether a neurosurgeon should do the procedure or make it a joint effort. It may well involve other specialty team effort approaches. It is essential to have an understanding of x-rays, CT, angiography, and MRI techniques and films. Sit with these specialists to learn more and help to avoid negative, misdiagnosis reports in the interest of the patient. Use judgement in helping the patient decide on ophthalmic or the more extensive neurosurgical approach after careful study and what is in their best interest. The team approach is used in well established medical centers with the ophthalmologist and neurosurgeon (or other specialist) working together in the best interest of the patient. This is more interesting and keeps the ophthalmologist in the mainstream of medicine. Images FIGURE 1 A FIGURE 1 B FIGURE 1 C FIGURE 2 FIGURE 3 A FIGURE 3 B FIGURE 3 C FIGURE 3 D FIGURE 4 A FIGURE 4 B FIGURE 5 A FIGURE 5 B FIGURE 6 A FIGURE 6 B FIGURE 7 A FIGURE 7 B FIGURE 7 C FIGURE 8 A FIGURE 8 B FIGURE 9

Kennedy, R E

1988-01-01

216

The Košice meteorite fall: Atmospheric trajectory, fragmentation, and orbit  

NASA Astrophysics Data System (ADS)

The Košice meteorite fall occurred in eastern Slovakia on February 28, 2010, 22:25 UT. The very bright bolide was imaged by three security video cameras from Hungary. Detailed bolide light curves were obtained through clouds by radiometers on seven cameras of the European Fireball Network. Records of sonic waves were found on six seismic and four infrasonic stations. An atmospheric dust cloud was observed the next morning before sunrise. After careful calibration, the video records were used to compute the bolide trajectory and velocity. The meteoroid, of estimated mass of 3500 kg, entered the atmosphere with a velocity of 15 km s-1 on a trajectory with a slope of 60° to the horizontal. The largest fragment ceased to be visible at a height of 17 km, where it was decelerated to 4.5 km s-1. A maximum brightness of absolute stellar magnitude about -18 was reached at a height of 36 km. We developed a detailed model of meteoroid atmospheric fragmentation to fit the observed light curve and deceleration. We found that Košice was a weak meteoroid, which started to fragment under the dynamic pressure of only 0.1 MPa and fragmented heavily under 1 MPa. In total, 78 meteorites were recovered in the predicted fall area during official searches. Other meteorites were found by private collectors. Known meteorite masses ranged from 0.56 g to 2.37 kg. The meteorites were classified as ordinary chondrites of type H5 and shock stage S3. The heliocentric orbit had a relatively large semimajor axis of 2.7 AU and aphelion distance of 4.5 ± 0.5 AU. Backward numerical integration of the preimpact orbit indicates possible large variations of the orbital elements in the past due to resonances with Jupiter.

Borovi?Ka, Ji?í; Tóth, Juraj; Igaz, Antal; Spurný, Pavel; Kalenda, Pavel; Haloda, Jakub; Svoreå, Ján; Kornoš, Leonard; Silber, Elizabeth; Brown, Peter; HusáRik, Marek

2013-10-01

217

Physical Properties of Fireball-Producing Earth-Impacting Meteoroids and Orbit Determination through Shadow Calibration of the Buzzard Coulee Meteorite Fall  

NASA Astrophysics Data System (ADS)

The physical properties of the meteoroid population were investigated through combining data from a number of fireball camera networks. PE values, as a measure of meteoroid strength, were calculated and linked with other observational criteria (Tisserand parameter, meteor shower identification). The historic divisions for fireball types based on the PE criterion were not observed in the large data set, but a correlation with source region was recognized. Meteor showers demonstrated different amounts of variation in PE values potentially related to the materials found in each parent comet. The trajectory and pre-fall orbit for the Buzzard Coulee meteoroid were determined through the calibration of shadows cast by the fireball. The method of using shadows to triangulate a trajectory was developed and evaluated. The best fit trajectory was coupled with an initial velocity of 18.0 km/s to compute the heliocentric orbit. Buzzard Coulee fell from a modestly inclined near-Earth Apollo orbit. It is the 12th fallen meteorite to be associated with an orbit.

Milley, Ellen Palesa

218

Geostationary Earth Orbit Satellite Model  

NSDL National Science Digital Library

The Geostationary Earth Orbit Satellite Model is a simple angular velocity model that uses Java3D for a realistic visualization of satellites in geostationary orbits. Students can view and explore the behavior of geostationary orbits, non-geostationary orbits, and non-physical orbits. This model tests the Java 3D implementation of the EJS 3D library. A warning message will appear if the Java 3D library is not available. The Geostationary Earth Orbit Satellite Model was developed using the Easy Java Simulations (EJS) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the jar file will run the program if Java is installed. You can modify this simulation if you have EJS installed by right-clicking within the map and selecting "Open Ejs Model" from the pop-up menu item.

Wee, Loo K.

2012-04-08

219

On halo orbits spacecraft stabilization  

Microsoft Academic Search

The paper deals with the application of recent non-linear control techniques to the problem of tracking and maintaining a given satellite on prescribed orbits around the so-called translunar libration point L2. Such orbits, known in literature as Halo Orbits, have the property of ensuring visibility both from the dark side of the Moon and from Earth at any time. Their

P. Di Giamberardino; S. Monaco

1996-01-01

220

Orbital myositis: Diagnosis and management  

Microsoft Academic Search

Orbital myositis is an inflammatory process that primarily involves the extraocular muscles and most commonly affects young\\u000a adults in the third decade of life, with a female predilection. Clinical characteristics of orbital myositis include orbital\\u000a and periorbital pain, ocular movement impairment, diplopia, proptosis, swollen eyelids, and conjunctival hyperemia. The most\\u000a common presentation is acute and unilateral, which initially responds to

Roberta M. S. Costa; Oana M. Dumitrascu; Lynn K. Gordon

2009-01-01

221

[Vascular tumors of the orbit].  

PubMed

Vascular tumors of the orbit include capillary hemangioma, cavernous hemangioma, hemolymphangioma, hemangiopericytoma and a few rare tumors. Capillary hemangioma and hemolymphangioma, occurring mainly in children, are covered in the chapter devoted to childhood tumors. In this chapter, cavernous hemangioma and hemangiopericytoma are discussed as well as rare vascular tumors. Although orbital varix is not a tumor, it is also considered because of the diagnostic problems and the close correlation of orbital varix with a true tumor: hemolymphangioma. PMID:20303554

Cophignon, J; d'Hermies, F; Civit, T

2010-01-01

222

Vascular tumors of the orbit  

Microsoft Academic Search

Eighty-five vascular lesions of the orbit examined and treated between 1963–1993 were reviewed retrospectively to reveal the types of vascular tumors, age and sex distribution, clinical characteristics, treatment options and prognosis. Capillary hemangioma was the most frequent orbital vascular tumor accounting for 37 of 85 cases making up 43.5% of the entire orbital masses. Cavernous hemangioma accounted for 35 cases

Ilhan Günalp; Kaan Gündüz

1995-01-01

223

Orbit synthesis for target satellites  

Microsoft Academic Search

The purpose of the study is to illustrate the orbit synthesis process for a hypothetical test of a direct-ascent-based kinetic energy weapon (KEW) against an instrumented test vehicle. Test arena and communications considerations for a ground-based directed energy weapon and a direct-ascent-based KEW are outlined, along with launch vehicle constraints, algorithms for off-nominal orbits, and thermal-control and orbit lifetime considerations.

Charles K. Wilkinson

1990-01-01

224

'Columbia Hills' from Orbit  

NASA Technical Reports Server (NTRS)

This view of the 'Columbia Hills' in Gusev Crater was made by draping an image from the Mars Orbiter Camera on NASA's Mars Global Surveyor orbiter (image E0300012 from that camera) over a digital elevation model that was derived from two Mars Orbiter Camera images (E0300012 and R0200357).

This unique view is helpful to the rover team members as they plan the journey of NASA's Mars Exploration Rover Spirit to the base of the Columbia Hills and beyond. Spirit successfully completed a three-month primary mission, and so far remains healthy in an extended mission of bonus exploration. As of sol 135 (on May 21, 2004), Spirit sits approximately 680 meters (0.4 miles) away from its first target at the western base of the hills, a spot informally called 'West Spur.' The team estimates that Spirit will reach West Spur by sol 146 (June 1, 2004). Spirit will most likely remain there for about a week to study the outcrops and rocks associated with this location.

When done there, Spirit will head approximately 620 meters (0.38 miles) to a higher-elevation location informally called 'Lookout Point.' Spirit might reach Lookout Point by around sol 165 (June 20, 2004). On the way, the rover will pass by and study ripple-shaped wind deposits that may reveal more information about wind processes on Mars.

Lookout Point will provide a great vantage point for scientists to remotely study the inner basin area of the Columbia Hills. This basin contains a broad range of interesting geological targets including the informally named 'Home Plate' and other possible layered outcrops. These features suggest that the hills contain rock layers. Spirit might investigate the layers to determine whether they are water-deposited sedimentary rock.

Once at Lookout Point, Spirit will acquire 360-degree panoramic images of the entire area to help define the rover's next steps. Assuming the rover stays healthy, Spirit will eventually drive down into the basin to get an up-close look at interesting features there.

2004-01-01

225

Mars Reconnaissance Orbiter Taking Shape  

NASA Technical Reports Server (NTRS)

Lockheed Martin Space Systems engineer Terry Kampmann (left) and lead technician Jack Farmerie work on assembly and test of NASA's Mars Reconnaissance Orbiter spacecraft bus in a cleanroom at the company's Denver facility. In coming months, the orbiter's science instruments will be integrated and tested, followed by environmental testing of the completed spacecraft. Launch of Mars Reconnaissance Orbiter is scheduled for August 2005.

The Mars Reconnaissance Orbiter project is managed for the NASA Science Mission Directorate, Washington, by the Jet Propulsion Laboratory, a division of the California Institute of Technology, Pasadena. Lockheed Martin Space Systems, Denver, is prime contractor for the project.

2004-01-01

226

Orbiter utilization as an ACRV  

NASA Technical Reports Server (NTRS)

Assuming that a Shuttle Orbiter could be qualified to serve long duration missions attached to Space Station Freedom in the capacity as an Assured Crew Return Vehicle (ACRV), a study was conducted to identify and examine candidate attach locations. Baseline, modified hardware, and new hardware design configurations were considered. Dual simultaneous Orbiter docking accommodation were required. Resulting flight characteristics analyzed included torque equilibrium attitude (TEA), microgravity environment, attitude controllability, and reboost fuel requirements. The baseline Station could not accommodate two Orbiters. Modified hardware configurations analyzed had large TEA's. The utilization of an oblique docking mechanism best accommodated an Orbiter as an ACRV.

Cruz, Jonathan N.; Heck, Michael L.; Kumar, Renjith R.; Mazanek, Daniel D.; Troutman, Patrick A.

1990-01-01

227

Orbital order in vanadium spinels  

Microsoft Academic Search

Motivated by recent theoretical and experimental controversy, we present a\\u000atheoretical study to clarify the orbital symmetry of the ground state of\\u000avanadium spinel oxides AV$_2$O$_4$ (A=Zn, Mg, Cd). The study is based on an\\u000aeffective Hamiltonian with spin-orbital superexchange interaction and a local\\u000aspin-orbit coupling term. We construct a classical phase-diagram and prove the\\u000acomplex orbital nature of the

S. Di Matteo; G. Jackeli; N. B. Perkins

2005-01-01

228

Orbiter emergency crew escape system  

NASA Technical Reports Server (NTRS)

Two conventional ejection seats were incorporated into the first two orbiter vehicles to provide the crew with emergency ejection capability during the flight test programs. To avoid extensive development and test costs, existing ejection seats were selected and minimum modifications were made to accommodate the orbiter application. The new components and modifications were qualified at the component level, and a minimum sled test program was conducted to verify the orbiter installation and validate the six degree-of-freedom analysis. The system performance was certified and the orbital flight test capability was established by analysis.

Lofland, W. W.

1980-01-01

229

Orbiter Servicer Rendezvous Simulation (ORSIM)  

NASA Astrophysics Data System (ADS)

Orbiter Servicer Rendezvous Simulation (ORSIM) is an automated tool that simulates sequential transfer maneuvers of an orbital maneuvering vehicle (OMV) transporting orbital replaceable units from a space-based depot, or logistics platform, to higher altitude SDI sdatellites. ORSIM calculates OMV energy expenditures (velocity changes) and event histories for various combinations of user-selected orbital transfer maneuvers. Additionally, ORSIM determines the optimal configuration/quantities of logistics platforms and OMVs which conform to the dynamics of differential nodal precession, given user-prescribed values of the scheduled maintenance cycle and required servicing times. ORSIM is coded in FORTRAN-77 and is resident on an IBM PC/AT.

Amato, Amiel; Hoffman, Mickie D.

230

Accelerated testing for synchronous orbits  

NASA Technical Reports Server (NTRS)

Degradation of batteries during synchronous orbits is analyzed. Discharge and recharge rates are evaluated. The functional relationship between charge rate and degradation is mathematically determined.

Mcdermott, P.

1981-01-01

231

Orbital science's 'Bermuda Triangle'  

NASA Astrophysics Data System (ADS)

The effects of a part of the inner Van Allen belt lying closest to the earth, known as the South Atlantic Anomaly (SAA) upon spacecraft including the Hubble Space Telescope (HST), are discussed. The area consists of positively charged ions and electrons from the Van Allen Belt which become trapped in the earth's dipole field. Contor maps representing the number of protons per square centimeter per second having energies greater than 10 million electron volts are presented. It is noted that the HST orbit causes it to spend about 15 percent of its time in the SAA, but that, unlike the experience with earlier spacecraft, the satellite's skin, internal structure, and normal electronic's packaging provides sufficient protection against eletrons, although some higher energy protons still get through. Various charged particle effects which can arise within scientific instruments including fluorescence, Cerenkov radiation, and induced radioactivity are described.

Sherrill, Thomas J.

1991-02-01

232

Solar Orbiter science  

NASA Astrophysics Data System (ADS)

A summary is given of the scientific advances that are expected from the Solar Orbiter. There will be unexpected discoveries from exploring new regions of the Sun for the first time - namely, the polar regions, the inner solar wind and increasing the current special resolution by an order of magnitude. However, it is also likely to make substantial advances or to provide definitive answers to several basic physics questions that are of substantial importance for our understanding of the wider universe. These include: the effect of the Sun on the Earth's climate; the structure of the solar interior and the nature of the solar dynamos; the nature and behaviour of the fundamental magnetic structures of the solar surface; the nature of the transition region; the drivers for the solar wind; and the mechanisms for heating the corona.

Priest, E. R.

2001-09-01

233

Skylab Orbiter Workshop Illustration  

NASA Technical Reports Server (NTRS)

This cutaway illustration shows the characteristics and basic elements of the Skylab Orbiter Workshop (OWS). The OWS was divided into two major compartments. The lower level provided crew accommodations for sleeping, food preparation and consumption, hygiene, waste processing and disposal, and performance of certain experiments. The upper level consisted of a large work area and housed water storage tanks, a food freezer, storage vaults for film, scientific airlocks, mobility and stability experiment equipment, and other experimental equipment. The compartment below the crew quarters was a container for liquid and solid waste and trash accumulated throughout the mission. A solar array, consisting of two wings covered on one side with solar cells, was mounted outside the workshop to generate electrical power to augment the power generated by another solar array mounted on the solar observatory. Thrusters were provided at one end of the workshop for short-term control of the attitude of the space station.

1972-01-01

234

Orbital xanthogranuloma in adults.  

PubMed Central

The onset of periorbital xanthogranuloma in adults is rare and may be accompanied by haematological abnormalities and malignancy. The appearance of the eyelid lesions is virtually diagnostic, producing readily recognisable diffuse, yellow plaques, and affected patients should be investigated and reviewed regularly for systemic disease. Three cases are described, in which periorbital cutaneous plaques were associated with abnormal tissues in the superior part of the orbit; these abnormal tissues caused displacement or restricted movement of the globe or upper eyelid. The possibility that two cases represent a necrobiotic type of xanthogranuloma is presented. Nine years after the onset of xanthogranuloma one patient developed non-Hodgkin's lymphoma. A multiple-drug regimen of systemic chemotherapy, given for lymphoma, caused a marked clinical reduction in the periorbital xanthogranuloma. Images

Rose, G. E.; Patel, B. C.; Garner, A.; Wright, J. E.

1991-01-01

235

Calculating Trajectories And Orbits  

NASA Technical Reports Server (NTRS)

Double-Precision Trajectory Analysis Program, DPTRAJ, and Orbit Determination Program, ODP, developed and improved over years to provide highly reliable and accurate navigation capability for deep-space missions like Voyager. Each collection of programs working together to provide desired computational results. DPTRAJ, ODP, and supporting utility programs capable of handling massive amounts of data and performing various numerical calculations required for solving navigation problems associated with planetary fly-by and lander missions. Used extensively in support of NASA's Voyager project. DPTRAJ-ODP available in two machine versions. UNIVAC version, NPO-15586, written in FORTRAN V, SFTRAN, and ASSEMBLER. VAX/VMS version, NPO-17201, written in FORTRAN V, SFTRAN, PL/1 and ASSEMBLER.

Alderson, Daniel J.; Brady, Franklyn H.; Breckheimer, Peter J.; Campbell, James K.; Christensen, Carl S.; Collier, James B.; Ekelund, John E.; Ellis, Jordan; Goltz, Gene L.; Hintz, Gerarld R.; Legerton, Victor N.; Mccreary, Faith A.; Mitchell, Robert T.; Mottinger, Neil A.; Moultrie, Benjamin A.; Moyer, Theodore D.; Rinker, Sheryl L.; Ryne, Mark S.; Stavert, L. Robert; Sunseri, Richard F.

1989-01-01

236

Orbiting Carbon Observatory  

NASA Technical Reports Server (NTRS)

Human impact on the environment has produced measurable changes in the geological record since the late 1700s. Anthropogenic emissions of CO2 today may cause the global climate to depart for its natural behavior for many millenia. CO2 is the primary anthropogenic driver of climate change. The Orbiting Carbon Observatory goals are to help collect measurements of atmospheric CO2, answering questions such as why the atmospheric CO2 buildup varies annually, the roles of the oceans and land ecosystems in absorbing CO2, the roles of North American and Eurasian sinks and how these carbon sinks respond to climate change. The present carbon cycle, CO2 variability, and climate uncertainties due atmospheric CO2 uncertainties are highlighted in this presentation.

Miller, Charles E.

2005-01-01

237

Geology orbiter comparison study  

NASA Technical Reports Server (NTRS)

Instrument requirements of planetary geology orbiters were examined with the objective of determining the feasibility of applying standard instrument designs to a host of terrestrial targets. Within the basic discipline area of geochemistry, gamma-ray, X-ray fluorescence, and atomic spectroscopy remote sensing techniques were considered. Within the discipline area of geophysics, the complementary techniques of gravimetry and radar were studied. Experiments using these techniques were analyzed for comparison at the Moon, Mercury, Mars and the Galilean satellites. On the basis of these comparative assessments, the adaptability of each sensing technique was judged as a basic technique for many targets, as a single instrument applied to many targets, as a single instrument used in different mission modes, and as an instrument capability for nongeoscience objectives.

Cutts, J. A. J.; Blasius, K. R.; Davis, D. R.; Pang, K. D.; Shreve, D. C.

1977-01-01

238

Orbit Determination Toolbox  

NASA Technical Reports Server (NTRS)

The Orbit Determination Toolbox is an orbit determination (OD) analysis tool based on MATLAB and Java that provides a flexible way to do early mission analysis. The toolbox is primarily intended for advanced mission analysis such as might be performed in concept exploration, proposal, early design phase, or rapid design center environments. The emphasis is on flexibility, but it has enough fidelity to produce credible results. Insight into all flight dynamics source code is provided. MATLAB is the primary user interface and is used for piecing together measurement and dynamic models. The Java Astrodynamics Toolbox is used as an engine for things that might be slow or inefficient in MATLAB, such as high-fidelity trajectory propagation, lunar and planetary ephemeris look-ups, precession, nutation, polar motion calculations, ephemeris file parsing, and the like. The primary analysis functions are sequential filter/smoother and batch least-squares commands that incorporate Monte-Carlo data simulation, linear covariance analysis, measurement processing, and plotting capabilities at the generic level. These functions have a user interface that is based on that of the MATLAB ODE suite. To perform a specific analysis, users write MATLAB functions that implement truth and design system models. The user provides his or her models as inputs to the filter commands. The software provides a capability to publish and subscribe to a software bus that is compliant with the NASA Goddard Mission Services Evolution Center (GMSEC) standards, to exchange data with other flight dynamics tools to simplify the flight dynamics design cycle. Using the publish and subscribe approach allows for analysts in a rapid design center environment to seamlessly incorporate changes in spacecraft and mission design into navigation analysis and vice versa.

Carpenter, James R.; Berry, Kevin; Gregpru. Late; Speckman, Keith; Hur-Diaz, Sun; Surka, Derek; Gaylor, Dave

2010-01-01

239

Orbital myositis in scleritis  

PubMed Central

Aims: To investigate the association between scleritis and myositis. Methods: Retrospective, non-comparative case series. Records and ultrasonograms were examined of 132 patients, with a diagnosis of episcleritis or scleritis, who attended the ophthalmology department at Leiden University Medical Center between 1997 and 2000. 103 were eligible for comprehensive examination. Medical records were evaluated. Ultrasonography was performed in all patients diagnosed with episcleritis or scleritis. Clinical features, precipitating factors, systemic associations, ocular complications, treatment, and outcome of each patient were assessed. Results: Of the 103 patients, 27 (26.2%) had episcleritis and 76 (73.8%) had scleritis. Myositis was found to be present in 11 patients. It was present in 14.5% of all patients with scleritis and 30.5% of those in whom the posterior sclera was affected. The presence of the associated myositis did not worsen the visual prognosis and the presence of myositis was not associated with other systemic diseases. There were no cases of unilateral scleritis with bilateral orbital myositis. During an attack ocular complications were more common in patients with scleritis and myositis (64%) than in patients with scleritis alone (30.4%), indicating a more diffuse and potentially dangerous inflammation. There was no evidence that the inflammatory changes in the orbit had spread to involve the sclera, so it is assumed that the muscle changes are an extension of a generalised response to intense inflammation of the episclera and sclera. Conclusion: This study found a frequent association between myositis and scleritis. Prognosis for vision was not affected by coexistence of myositis.

Boonman, Z F H M; de Keizer, R J W; Graniewski-Wijnands, H S; Watson, P G

2003-01-01

240

On-orbit performance of the Orbital Express Capture System  

NASA Astrophysics Data System (ADS)

The Orbital Express Capture System (OECS) is one of the key technologies successfully demonstrated as part of the Orbital Express Demonstration System flight operations that took place between March and July, 2007. The OECS supported all demate, capture and berthing activities throughout the span of on-orbit activities, with no anomalies. This paper will briefly review the Orbital Express (OE) program, including goals, key milestones & events and other major subsystems particularly relevant to the OECS performance. A summary of the major activities in the Virtual System Integration process, as applied to the OECS, to ultimately verify satisfactory pre-flight performance, will be presented. Finally, actual on-orbit performance of the OECS will be described.

Motaghedi, Pejmun

2008-05-01

241

Orbital Fluctuations and Orbital Flipping in RVO3 Perovskites  

SciTech Connect

The effect of the average A-site ionic radius hIRi and variance on the orbital and magnetic order in R3+-doped YVO3 was studied in Y1-xLaxVO3 and Y1-x(La0.2337Lu0.7663)xVO3 with fixed . The orbital flipping temperature T_CG increases nonlinearly with increasing R-site variance, indicating that the V-O-V bond angle is not the primary driving force stabilizing the C-type orbitally ordered phase. The suppressed thermal conductivity in the G-type orbitally ordered phase signals some remaining orbital randomness that is enhanced by t2 and et hybridization in 3T_1g site symmetry.

Yan, J.-Q. [Ames Laboratory; Zhou, J.-S. [University of Texas, Austin; Goodenough, J. B. [University of Texas, Austin; Ren, Y. [Argonne National Laboratory (ANL); Cheng, J. G. [Harbin Institute of Technology; Zarestky, Jerel L [ORNL; Garlea, Vasile O [ORNL; Liobet, A. [Los Alamos National Laboratory (LANL); Zhou, H. D. [University of Texas, Austin; Sui, Y. [Harbin Institute of Technology; Su, W. H. [Harbin Institute of Technology; McQueeney, R. J. [Ames Laboratory

2007-01-01

242

Optical performance of the 100-sq deg field-of-view telescope for NASA's Kepler exoplanet mission  

NASA Astrophysics Data System (ADS)

Kepler is NASA's first space mission dedicated to the study of exoplanets. The primary scientific goal is statistical - to estimate the frequency of planetary systems associated with sun-like stars, especially the detection of earth-size planets in the Habitable Zones. Kepler was launched into an Earth-trailing heliocentric "drift-away" orbit (period = 372 days) in March 2009. The instrument detects the faint photometric signals of transits of planets across the stellar disks of those systems with orbital planes fortuitously oriented in our line-of-sight. Since the probability of such alignments is small Kepler must observe a large number of stars. In fact, Kepler is monitoring approximately 150,000 stars with a 30-minute cadence. These scientific requirements led to the choice of a classical Schmidt telescope, and requirements on field-of-view (FOV), throughput, spectral bandpass, image quality, scattered light, thermal and opto-mechanical stability and in-flight adjustment authority. We review the pre-launch integration, alignment and test program, and we describe the in-flight commissioning that optimized the optical performance of the observatory. The stability of the flight system has enabled increasing recognition of small effects and increasing sophistication in data processing algorithms. Astrophysical noise arising from intrinsic stellar variability is now the dominant term in the photometric error budget.

Ebbets, D.; Atcheson, P.; Stewart, C.; Spuhler, P.; van Cleve, J.; Bryson, S.

2011-09-01

243

Orbiter-orbiter and orbiter-lander tracking using same-beam interferometry  

NASA Technical Reports Server (NTRS)

Two spacecraft orbiting Mars will subtend a small angle as viewed from Earth. This angle will usually be smaller than the beam width of a single radio antenna. Thus the two spacecraft may be tracked simultaneously by a single Earth-based antenna. The same-beam interferometry (SBI) technique involves using two widely separated antennas, each observing the two spacecraft, to produce a measurement of the angular separation of the two spacecraft in the plane of the sky. The information content of SBI data is thus complementary to the line-of-sight information provided by conventional Doppler data. The inclusion of SBI data with the Doppler data in a joint orbit estimation procedure can desensitize the solution to gravity mismodeling and result in improved orbit determination accuracy. This article presents an overview of the SBI technique, a measurement error analysis, and an error covariance analysis of some examples of the application of SBI to orbit determination. For hypothetical scenarios involving the Mars Observer and the Russian Mars '94 spacecraft, orbit determination accuracy improvements of up to an order of magnitude are predicted, relative to the accuracy that can be obtained by using only Doppler data acquired separately from each spacecraft. Relative tracking between a Mars orbiter and a lander fixed on the surface of Mars is also studied. Results indicate that the lander location may be determined to a few meters, while the orbiter ephemeris may be determined with accuracy similar to the orbiter-orbiter case.

Folkner, W. M.; Border, J. S.

1992-01-01

244

Multimodality imaging of the orbit  

PubMed Central

The role of imaging is well established in the evaluation of orbital diseases. Ultrasonography, Computed tomography and Magnetic resonance imaging are complementary modalities, which allow direct visualization of regional anatomy, accurate localization and help to characterize lesions to make a reliable radiological diagnosis. The purpose of this pictorial essay is to highlight the imaging features of commonly encountered pathologies which involve the orbit.

Hande, Pradipta C; Talwar, Inder

2012-01-01

245

Interacting Binaries with Eccentric Orbits  

Microsoft Academic Search

The Roche model has served for a long time as a fundamental tool to study the interactions and observational characteristics of the components of gravitational two-body systems. More often than not, applications of this model are built on the assumption that the orbit of the system is circular and that the system components are rotating synchronously with the orbital motion.

Jeremy F. Sepinsky; B. Willems; V. Kalogera

2006-01-01

246

Medium and High Altitude Orbits  

Microsoft Academic Search

A communication satellite in Medium and High Altitude Orbits must be visible from the regions concerned during the period when it is desired to provide a links for Fixed (FSS) and Mobile Satellite Service (MSS), what can vary from a few to 24 hours per day. These kinds of orbits are circular and are in function to cover a given

S. D. Ilcev

2010-01-01

247

Satellite services and orbital retrieval  

NASA Technical Reports Server (NTRS)

Within the capabilities of the Space Shuttle Orbiter, a broad range of services which can be made available to the satellite user community as summarized. Payload deployment, close proximity retrieval, and a number of other mission related functions are discussed. The focus here is on close proximity retrieval and retrieval of payloads in higher energy low Earth orbits.

Adornato, R. J.

1985-01-01

248

Orbital evolution around irregular bodies  

Microsoft Academic Search

The new profiles of the space missions aimed at asteroids and comets, moving from fly-bys to rendezvous and orbiting, call for new spaceflight dynamics tools capable of propagating orbits in an accurate way around these small irregular objects. Moreover, interesting celestial mechanics and planetary science problems, requiring the same sophisticated tools, have been raised by the first images of asteroids

A. Rossi; F. Marzari; P. Farinella

1999-01-01

249

Effects of low earth orbit  

Microsoft Academic Search

The effects of low earth orbit on the Long-Duration Exposure Facility (LDEF) spacecraft are reported. The LDEF spacecraft was deployed in low earth orbit in 1984 and was retrieved in 1990. The structure and design of LDEF is described. The dose of ionizing radiation received, data obtained, and its effects on the satellite are discussed. Atomic oxygen surface effects, oxygen

Lawrence E. Murr; William H. Kinard

1993-01-01

250

Organics, Earth orbit and astrobiology  

Microsoft Academic Search

Space technology provides the vehicle for transporting terrestrial organic matter and minerals in Earth orbit in order to study in situ their responses to space conditions and to atmospheric entry. Amino acids and peptides were exposed in Earth orbit during two Biopan ESA flights (1994, 1997) and during the CNES Perseus-Exobiologie mission (1999) with exposure times of 14, 10 and

A. Brack

2004-01-01

251

Safety in earth orbit study  

NASA Technical Reports Server (NTRS)

Safety aspects are studied of the space shuttle orbiter, the shuttle payloads, and space stations in earth orbital operations. The tasks generated safety requirements, guidelines, recommendations, and conceptual safety devices. The tasks studied were: hazardous payloads, docking, onboard survivability tumbling spacecraft, and escape and rescue operations.

1972-01-01

252

Origin of Pluto's Peculiar Orbit.  

National Technical Information Service (NTIS)

The origin of Pluto's unusual orbit - the most eccentric and inclined of all the planets - remains a mystery. The orbits of Pluto and Neptune overlap, but close approaches of these two planets are prevented by the existence of a resonance condition: Pluto...

R. Malhotra

1993-01-01

253

General relativity and satellite orbits  

NASA Technical Reports Server (NTRS)

The general relativistic correction to the position of a satellite is found by retaining Newtonian physics for an observer on the satellite and introducing a potential. The potential is expanded in terms of the Keplerian elements of the orbit and substituted in Lagrange's equations. Integration of the equations shows that a typical earth satellite with small orbital eccentricity is displaced by about 17 cm. from its unperturbed position after a single orbit, while the periodic displacement over the orbit reaches a maximum of about 3 cm. The moon is displaced by about the same amounts. Application of the equations to Mercury gives a total displacement of about 58 km. after one orbit and a maximum periodic displacement of about 12 km.

Rubincam, D. P.

1975-01-01

254

Pseudosymmetry analysis of molecular orbitals.  

PubMed

We introduce a pseudosymmetry analysis of molecular orbitals by means of the newly proposed irreducible representation measures. To do that we define first what we consider as molecular pseudosymmetry and the relationships of this concept with those of approximate symmetry and quasisymmetry. We develop a general algorithm to quantify the pseudosymmetry content of a given object within the framework of the finite group algebra. The obtained mathematical expressions are able to decompose molecular orbitals by means of the irreducible representations of any reference symmetry point group. The implementation and usefulness of the pseudosymmetry analysis of molecular orbitals is demonstrated in the study of ? and ? orbitals in planar and nonplanar polycyclic aromatic hydrocarbons and the t2 g and eg character of the d-orbitals in the [FeH6](3-) anion in its high spin state along the Bailar twist pathway. PMID:23436743

Casanova, David; Alemany, Pere; Falceto, Andrés; Carreras, Abel; Alvarez, Santiago

2013-06-01

255

HEO space debris orbit predictions.  

NASA Astrophysics Data System (ADS)

HEO (Highly Elliptical Orbit) satellites are objects with an elliptic orbit with a low-altitude perigee and a high-altitude apogee. Perigee mainly cross the LEO orbits and apogee reaches regions above GEO orbits. Number of satellites on the orbits are old racket bodies and other space debris. Most of HEO objects has the eccentricity more than 0.7. Many trackable objects are included in the NORAD TLE Catalogue but much more small debris exist which we could not track. Objects on as highly elliptical orbit are very danger for satellites in LEO region because of increasing velocity near the perigee. In order to calculate the trajectory of space debris we have to take into account force model consisting of geopotential, luni-solar effects, solar radiation pressure and for objects with low-altitude of perigee, atmospheric drag. This last perturbation is very important to calculate orbits with high accuracy but also one of the hardest to predict. Many atmospheric space debris objects parameters should be taken into account in this case, but we do not have sufficient data from observations, in particular S/M (area-to-mass) ratio. Fortunately we have some archival data for some debris included in TLE Catalogue, which are very helpful to estimate the approximate value of the parameter. In this paper we present the results of calculations of orbit predictions for short and medium time span (up to several weeks). We tried to designate the S/M parameter for some HEO objects from archival data from the TLE Catalogue and predict its orbital elements for several weeks. With better knowledge about approximate mean value of the S/M parameter we are able to improve the accuracy of predicted orbits.

Gregorowicz, Dorota; Pospieszynski, Remigiusz; Golembiewska, Justyna; Wnuk, Edwin

2012-07-01

256

The orbit design of MUSES mission  

Microsoft Academic Search

This paper describes the preliminary orbit design of MUSES mission in the early 1990s. This will be the first lunar mission for ISAS employing a lunar gravity-assist technique. The entire orbit is constructed by three major portions: the launch and parking orbit, the translunar orbit, and the lunar swingby orbit. Taking into account several design requirements such as a three

Toshimitsu Nishimura; Hiroki Matsuo; Kuninori Uesugi; Junichiro Kawaguchi; Hiroki Yokota

1986-01-01

257

Orbiter Camera Payload System  

NASA Technical Reports Server (NTRS)

Components for an orbiting camera payload system (OCPS) include the large format camera (LFC), a gas supply assembly, and ground test, handling, and calibration hardware. The LFC, a high resolution large format photogrammetric camera for use in the cargo bay of the space transport system, is also adaptable to use on an RB-57 aircraft or on a free flyer satellite. Carrying 4000 feet of film, the LFC is usable over the visible to near IR, at V/h rates of from 11 to 41 milliradians per second, overlap of 10, 60, 70 or 80 percent and exposure times of from 4 to 32 milliseconds. With a 12 inch focal length it produces a 9 by 18 inch format (long dimension in line of flight) with full format low contrast resolution of 88 lines per millimeter (AWAR), full format distortion of less than 14 microns and a complement of 45 Reseau marks and 12 fiducial marks. Weight of the OCPS as supplied, fully loaded is 944 pounds and power dissipation is 273 watts average when in operation, 95 watts in standby. The LFC contains an internal exposure sensor, or will respond to external command. It is able to photograph starfields for inflight calibration upon command.

1980-01-01

258

VSOP-2 Orbit Determination  

NASA Astrophysics Data System (ADS)

Precise orbit determination (POD) is a key factor to enable phase referencing observations with Astro-G. A POD accuracy of 30 cm is required for efficient X-band phase referencing observations, accuracy of 6 cm for K-band observations, and accuracy of 3 cm for Q-band observations. For the POD, Astro-G will be equipped with a GPS/Galileo receiver and a SLR (Satellite Laser Ranging) retroreflector array. Four POD antennas will be equipped on four sides of the satellite body, to cover all directions. The SLR will be used as a complement to the GPS at middle-to-high altitude. Because the refroreflector array should always face to the Earth direction, it will be set up on the Ka-link antenna gimbal. The most significant perturbing force for the Astro-G is solar radiation pressure (SRP). The reflectivity of each surface component should be preliminary measured in detail to model the SRP. The estimated achievable POD accuracy at apogee is 10 ˜ 30 cm in nominal case. Phase referencing observations in K- or Q-band can be performed if the enough amount of SLR tracking data can be obtained at high altitudes.

Takeuchi, H.; VSOP-2 Orbit Determination Sub-Working Group

2009-08-01

259

Precision Orbit Determination for the Lunar Reconnaissance Orbiter  

NASA Astrophysics Data System (ADS)

The Lunar Reconnaissance Orbiter (LRO) spacecraft was launched on June 18, 2009. In mid-September 2009, the spacecraft orbit was changed from its commissioning orbit (30 x 216 km polar) to a quasi-frozen polar orbit with an average altitude of 50km (+-15km). One of the goals of the LRO mission is to develop a new lunar reference frame to facilitate future exploration. Precision Orbit Determination is used to achieve the accuracy requirements, and to precisely geolocate the high-resolution datasets obtained by the LRO instruments. In addition to the tracking data most commonly used to determine spacecraft orbits in planetary missions (radiometric Range and Doppler), LRO benefits from two other types of orbital constraints, both enabled by the Lunar Orbiter Laser Altimeter (LOLA) instrument. The altimetric data collected as the instrument's primary purpose can be used to derive constraints on the orbit geometry at the times of laser groundtrack intersections (crossovers). The multi-beam configuration and high firing-rate of LOLA further improves the strength of these crossovers, compared to what was possible with the MOLA instrument onboard Mars Global Surveyor (MGS). Furthermore, one-way laser ranges (LR) between Earth International Laser Ranging Service (ILRS) stations and the spacecraft are made possible by the addition of a small telescope mounted on the spacecraft high-gain antenna. The photons received from Earth are transmitted to one LOLA detector by a fiber optics bundle. Thanks to the accuracy of the LOLA timing system, the precision of 5-s LR normal points is below 10cm. We present the first results of the Precision Orbit Determination (POD) of LRO through the commissioning and nominal phases of the mission. Orbit quality is discussed, and various gravity fields are evaluated with the new (independent) LRO radio tracking data. The altimetric crossovers are used as an independent data type to evaluate the quality of the orbits. The contribution of the LR data is assessed. Multi-arc solutions over entire months are presented, which allow to strengthen the LR data because fewer clock-related parameters need to be adjusted. Finally, a preliminary 1-month solution with altimetric crossover constraints is evaluated and discussed

Lemoine, F. G.; Mazarico, E.; Rowlands, D. D.; Torrence, M. H.; McGarry, J. F.; Neumann, G. A.; Mao, D.; Smith, D. E.; Zuber, M. T.

2010-05-01

260

Lifetimes of lunar satellite orbits  

NASA Technical Reports Server (NTRS)

The Space Exploration Initiative has generated a renewed interest in lunar mission planning. The lunar missions currently under study, unlike the Apollo missions, involve long stay times. Several lunar gravity models have been formulated, but mission planners do not have enough confidence in the proposed models to conduct detailed studies of missions with long stay times. In this report, a particular lunar gravitational model, the Ferrari 5 x 5 model, was chosen to determine the lifetimes for 100-km and 300-km perilune altitude, near-circular parking orbits. The need to analyze orbital lifetimes for a large number of initial orbital parameters was the motivation for the formulation of a simplified gravitational model from the original model. Using this model, orbital lifetimes were found to be heavily dependent on the initial conditions of the nearly circular orbits, particularly the initial inclination and argument of perilune. This selected model yielded lifetime predictions of less than 40 days for some orbits, and other orbits had lifetimes exceeding a year. Although inconsistencies and limitations are inherent in all existing lunar gravity models, primarily because of a lack of information about the far side of the moon, the methods presented in this analysis are suitable for incorporating the moon's nonspherical gravitational effects on the preliminary design level for future lunar mission planning.

Meyer, Kurt W.; Buglia, James J.; Desai, Prasun N.

1994-01-01

261

Geostationary orbit determination using SATRE  

NASA Astrophysics Data System (ADS)

A new strategy of precise orbit determination (POD) for GEO (Geostationary Earth Orbit) satellite using SATRE (SAtellite Time and Ranging Equipment) is presented. Two observation modes are proposed and different channels of the same instruments are used to construct different observation modes, one mode receiving time signals from their own station and the other mode receiving time signals from each other for two stations called pairs of combined observations. Using data from such a tracking network in China, the results for both modes are compared. The precise orbit determination for the Sino-1 satellite using the data from 6 June 2005 to 13 June 2005 has been carried out in this work. The RMS (Root-Mean-Square) of observing residuals for 3-day solutions with the former mode is better than 9.1 cm. The RMS of observing residuals for 3-day solutions with the latter mode is better than 4.8 cm, much better than the former mode. Orbital overlapping (3-day orbit solution with 1-day orbit overlap) tests show that the RMS of the orbit difference for the former mode is 0.16 m in the radial direction, 0.53 m in the along-track direction, 0.97 m in the cross-track direction and 1.12 m in the 3-dimension position and the RMS of the orbit difference for the latter mode is 0.36 m in the radial direction, 0.89 m in the along-track direction, 1.18 m in the cross-track direction and 1.52 m in the 3-dimension position, almost the same as the former mode. All the experiments indicate that a meter-level accuracy of orbit determination for geostationary satellite is achievable.

Lei, Hui; Li, ZhiGang; Yang, XuHai; Wu, WenJun; Cheng, Xuan; Yang, Ying; Feng, ChuGang

2011-09-01

262

Orbital, subconjunctival, and subcutaneous emphysema after an orbital floor fracture  

PubMed Central

A 16-year-old boy presented to the emergency department with the complaint of a sudden, painful left eye and proptosis after an episode of sneezing. A few hours earlier, he had sustained a blunt trauma to the left orbit as the result of a fistfight. The initial examination showed subcutaneous and subconjunctival emphysema. Visual acuity in the left eye was 20/30 (0.67), the pupils were reactive with no relative afferent pupillary defect, and there were mild limitations in levoduction and supraduction. A slit-lamp examination showed normal anterior and posterior segments with an intraocular pressure of 26 mmHg. An orbital computed tomography scan showed orbital, subconjunctival, and subcutaneous emphysema associated with a small fracture of the orbital floor. Following conservative management with broad-spectrum oral antibiotics, a topical antiglaucoma drug, and lubricating eye drops, the patient improved dramatically within one week.

Ababneh, Osama H

2013-01-01

263

Minimum Orbits about the Planet Venus.  

National Technical Information Service (NTIS)

An investigation is conducted into low orbiting satellites around the planet Venus with drag limited lifetimes. It is possible to specify combinations of orbital elements which result in orbital lifetimes in excess of some desired value. These combination...

J. J. Smith

1990-01-01

264

Orbiter Atlantis returns to KSC  

NASA Technical Reports Server (NTRS)

The Shuttle Carrier Aircraft gently lands its piggyback cargo - - orbiter Atlantis -- at the Shuttle Landing Facility. Atlantis returns home after a 10-month stay in the Palmdale, CA, orbiter processing facility undergoing extensive inspections and modifications. They included several upgrades enabling it to support International Space Station missions, such as adding an external airlock for ISS docking missions and installing thinner, lighter thermal protection blankets for weight reduction which will allow it to haul heavier cargo. The flight from Palmdale included a fueling stop in Ft. Hood, TX, and overnight stay at Ft. Campbell, KY. Atlantis will undergo preparations in the Orbiter Processing Facility at KSC for its planned flight in June 1999.

1998-01-01

265

Orbital, Rotational, and Climatic Interactions  

NASA Technical Reports Server (NTRS)

The report of an international meeting on the topic of Orbital, Rotational, and Climatic Interactions, which was held 9-11 Jul. 1991 at the Johns Hopkins University is presented. The meeting was attended by 22 researchers working on various aspects of orbital and rotational dynamics, paleoclimate data analysis and modeling, solid-Earth deformation studies, and paleomagnetic analyses. The primary objective of the workshop was to arrive at a better understanding of the interactions between the orbital, rotational, and climatic variations of the Earth. This report contains a brief introduction and 14 contributed papers which cover most of the topics discussed at the meeting.

Bills, Bruce G. (editor)

1992-01-01

266

JSC Orbital Debris Website Description  

NASA Technical Reports Server (NTRS)

Purpose: The website provides information about the NASA Orbital Debris Program Office at JSC, which is the lead NASA center for orbital debris research. It is recognized world-wide for its leadership in addressing orbital debris issues. The NASA Orbital Debris Program Office has taken the international lead in conducting measurements of the environment and in developing the technical consensus for adopting mitigation measures to protect users of the orbital environment. Work at the center continues with developing an improved understanding of the orbital debris environment and measures that can be taken to control its growth. Major Contents: Orbital Debris research is divided into the following five broad efforts. Each area of research contains specific information as follows: 1) Modeling - NASA scientists continue to develop and upgrade orbital debris models to describe and characterize the current and future debris environment. Evolutionary and engineering models are described in detail. Downloadable items include a document in PDF format and executable software. 2) Measurements - Measurements of near-Earth orbital debris are accomplished by conducting ground-based and space-based observations of the orbital debris environment. The data from these sources provide validation of the environment models and identify the presence of new sources. Radar, optical and surface examinations are described. External links to related topics are provided. 3) Protection - Orbital debris protection involves conducting hypervelocity impact measurements to assess the risk presented by orbital debris to operating spacecraft and developing new materials and new designs to provide better protection from the environment with less weight penalty. The data from this work provides the link between the environment defined by the models and the risk presented by that environment to operating spacecraft and provides recommendations on design and operations procedures to reduce the risk as required. These data also help in the analysis and interpretation of impact features on returned spacecraft surfaces. 4) Mitigation - Controlling the growth of the orbital debris population is a high priority for NASA, the United States, and the major space-faring nations of the world to preserve near-Earth space for future generations. Mitigation measures can take the form of curtailing or preventing the creation of new debris, designing satellites to withstand impacts by small debris, and implementing operational procedures ranging from utilizing orbital regimes with less debris, adopting specific spacecraft attitudes, and even maneuvering to avoid collisions with debris. Downloadable items include several documents in PDF format and executable software.and 5) Reentry - Because of the increasing number of objects in space, NASA has adopted guidelines and assessment procedures to reduce the number of non-operational spacecraft and spent rocket upper stages orbiting the Earth. One method of postmission disposal is to allow reentry of these spacecraft, either from orbital decay (uncontrolled entry) or with a controlled entry. Orbital decay may be achieved by firing engines to lower the perigee altitude so that atmospheric drag will eventually cause the spacecraft to enter. However, the surviving debris impact footprint cannot be guaranteed to avoid inhabited landmasses. Controlled entry normally occurs by using a larger amount of propellant with a larger propulsion system to drive the spacecraft to enter the atmosphere at a steeper flight path angle. It will then enter at a more precise latitude, longitude, and footprint in a nearly uninhabited impact region, generally located in the ocean.

Johnson, Nicholas L.

2006-01-01

267

Independent Orbiter Assessment (IOA): Analysis of the orbital maneuvering system  

NASA Technical Reports Server (NTRS)

The results of the Independent Orbiter Assessment (IOA) of the Failure Modes and Effects Analysis (FMEA) and Critical Items List (CIL) are presented. The IOA approach features a top-down analysis of the hardware to determine failure modes, criticality, and potential critical items. To preserve independence, this analysis was accomplished without reliance upon the results contained within the NASA FMEA/CIL documentation. The independent analysis results for the Orbital Maneuvering System (OMS) hardware are documented. The OMS provides the thrust to perform orbit insertion, orbit circularization, orbit transfer, rendezvous, and deorbit. The OMS is housed in two independent pods located one on each side of the tail and consists of the following subsystems: Helium Pressurization; Propellant Storage and Distribution; Orbital Maneuvering Engine; and Electrical Power Distribution and Control. The IOA analysis process utilized available OMS hardware drawings and schematics for defining hardware assemblies, components, and hardware items. Each level of hardware was evaluted and analyzed for possible failure modes and effects. Criticality was asigned based upon the severity of the effect for each failure mode.

Prust, C. D.; Paul, D. J.; Burkemper, V. J.

1987-01-01

268

Orbital Evolution of ExtraSolar Giant Planets  

Microsoft Academic Search

The recent discoveries (Mayor and Queloz, 1995; Marcy and Butler, 1996; Butler and Marcy, 1996) of extra-solar giant planets (EGPs) at small heliocentric distances have prompted questions about the formation, evolution, and migration of these EGPs. The location of several EGPs at much less than 1 AU from their primaries has proved to be particularly problematic. Since it is thought

D. E. Trilling; W. Benz; T. Guillot; J. I. Lunine

1996-01-01

269

Pioneer Venus Orbiter Fluxgate Magnetometer  

Microsoft Academic Search

The fluxgate magnetometer on the Pioneer Venus orbiter spacecraft is described. Special features include gradiometer operation, on board despinning, a floating point processor and variable Nyquist filters. Initial operations have been entirely successful.

C. T. Russell; R. C. Snare; J. D. Means; R. C. Elphic

1980-01-01

270

Mars Reconnaissance Orbiter Interplanetary Navigation  

NASA Technical Reports Server (NTRS)

This viewgraph presentation reviews the Mars Reconnaissance Orbiter (MRO) interplanetary navigation. An interplanetary overview including dynamic models of outgassing, small force calibration and trending, solar radiation pressure and trajectory correction maneuvers are also described.

You, Tung-Han; Halsell, Allen; Graat, Eric J.; Highsmith, Dolan E.; Demcak, Stuart; Long, Stacia M.; Bhat, Ramachand S.; Mottinger, Neil A.; Higa, Earl; Jah, Moriba K.

2007-01-01

271

NASA Orbital Debris Baseline Populations  

NASA Technical Reports Server (NTRS)

The NASA Orbital Debris Program Office has created high fidelity populations of the debris environment. The populations include objects of 1 cm and larger in Low Earth Orbit through Geosynchronous Transfer Orbit. They were designed for the purpose of assisting debris researchers and sensor developers in planning and testing. This environment is derived directly from the newest ORDEM model populations which include a background derived from LEGEND, as well as specific events such as the Chinese ASAT test, the Iridium 33/Cosmos 2251 accidental collision, the RORSAT sodium-potassium droplet releases, and other miscellaneous events. It is the most realistic ODPO debris population to date. In this paper we present the populations in chart form. We describe derivations of the background population and the specific populations added on. We validate our 1 cm and larger Low Earth Orbit population against SSN, Haystack, and HAX radar measurements.

Krisko, Paula H.; Vavrin, A. B.

2013-01-01

272

Lunar orbital mass spectrometer experiment  

NASA Technical Reports Server (NTRS)

The design, development, manufacture, test and calibration of five lunar orbital mass spectrometers with the four associated ground support equipment test sets are discussed. A mass spectrometer was installed in the Apollo 15 and one in the Apollo 16 Scientific Instrument Module within the Service Module. The Apollo 15 mass spectrometer was operated with collection of 38 hours of mass spectra data during lunar orbit and 50 hours of data were collected during transearth coast. The Apollo 16 mass spectrometer was operated with collection of 76 hours of mass spectra data during lunar orbit. However, the Apollo 16 mass spectrometer was ejected into lunar orbit upon malfunction of spacecraft boom system just prior to transearth insection and no transearth coast data was possible.

Lord, W. P.

1971-01-01

273

Visualization of Molecular Orbitals: Formaldehyde  

ERIC Educational Resources Information Center

Describes a computer program that plots a solid" representation of molecular orbital charge density which can be used to analyze wave functions of molecules. Illustrated with diagrams for formaldehyde. (AL)

Olcott, Richard J.

1972-01-01

274

Aqua satellite orbiting the Earth  

NASA Video Gallery

This animation shows the Aqua satellite orbiting the Earth on August 27, 2005 by revealing MODIS true-color imagery for that day. This animation is on a cartesian map projection, so the satellite w...

275

How to Orbit the Earth.  

ERIC Educational Resources Information Center

Discusses the geometry, algebra, and logic involved in the solution of a "Mindbenders" problem in "Discover" magazine and applies it to calculations of satellite orbital velocity. Extends the solution of this probe to other applications of falling objects. (JM)

Quimby, Donald J.

1984-01-01

276

The orbit of Pluto's satellite  

NASA Technical Reports Server (NTRS)

Nineteen speckle interferometric observations of the Pluto system have been used to improve the determination of the orbital elements for Pluto's satellite. Calibration uncertainties appear to be the dominant source of error, but the observation of a partial occultation of the satellite by Pluto has been used to constrain the orbit solution. The orbital period is found to be in excellent agreement with the rotational period of the planet, reinforcing the belief that the system is completely tidally evolved. The orbital radius and period imply a total mass for the system of 6.8 + or - 0.5 x 10 to the -9th solar masses. Density constraints place an upper limit of 3615 + or - 90 km on the diameter of Pluto, while observations of the first mutual events establish a crude lower limit of about 2800 km.

Tholen, D. J.

1985-01-01

277

Conversion Of Classical Orbital Elements  

NASA Technical Reports Server (NTRS)

OSMEAN is sophisticated program that converts between osculating and mean classical orbital elements. Enables engineer to exploit advantages of each approach for design and planning or orbital trajectories and maneuvers. Converts mean elements to osculating elements or vice-versa. Conversion based on mathematical modeling of all first-order aspherical terrestrial, lunar, and solar gravitational perturbations plus second-order aspherical term based on second-degree central-body zonal perturbation. Written in FORTRAN 77.

Guinn, Joseph R.; Bhat, Ramachand S.; Vincent, Mark A.; Konopliv, Alexander S.

1994-01-01

278

Trojan orbits in secular resonances  

Microsoft Academic Search

A near equality between the nodal rates of suitably defined Trojan orbits and Jupiter represents an important type of a secular resonance. This case is realized by the model Sun-Jupiter-Saturn-Trojan, referred to the invariable plane. A second theoretical example is based on the elliptic three-body problem Sun-Jupiter-Trojan, where the vanishing nodal rate of a special Trojan orbit and the vanishing

R. Bien; J. Schubart

1984-01-01

279

Lightweight launches to low orbit  

NASA Astrophysics Data System (ADS)

The development and applicability of lightweight vehicles for launching payloads, such as communication and earth observation satellites and microgravity experiments, into nongeostationary orbit are examined. Consideration is given to the Scout, Conestoga, Industrial Launch Vehicle, Marianne, the Long March, Proton, and 'M'rockets. The use of payload recovery capsules to deliver payloads is discussed. Alternative lightweight orbital services, such as TOPAS based on the Scout rocket and the Space Kurier, for launching small payloads are being studied.

280

The Earth and Moon's Orbit  

NSDL National Science Digital Library

The following activities will help you explore how the earth and moon move around the sun. Activity 1: Go to the following activity below and then answer the questions below in your science journal. The Earth s Orbit Activity 1) How many months did it take to get the earth to orbit the sun one time? 2) Describe the motion of the earth and moon as it traveled around the sun? 3) How many hours ...

2009-02-28

281

Low Earth orbit communications satellite  

NASA Technical Reports Server (NTRS)

A current thrust in satellite communication systems considers a low-Earth orbiting constellations of satellites for continuous global coverage. Conceptual design studies have been done at the time of this design project by LORAL Aerospace Corporation under the program name GLOBALSTAR and by Motorola under their IRIDIUM program. This design project concentrates on the spacecraft design of the GLOBALSTAR low-Earth orbiting communication system. Overview information on the program was gained through the Federal Communications Commission licensing request. The GLOBALSTAR system consists of 48 operational satellites positioned in a Walker Delta pattern providing global coverage and redundancy. The operational orbit is 1389 km (750 nmi) altitude with eight planes of six satellites each. The orbital planes are spaced 45 deg., and the spacecraft are separated by 60 deg. within the plane. A Delta 2 launch vehicle is used to carry six spacecraft for orbit establishment. Once in orbit, the spacecraft will utilize code-division multiple access (spread spectrum modulation) for digital relay, voice, and radio determination satellite services (RDSS) yielding position determination with accuracy up to 200 meters.

Moroney, D.; Lashbrook, D.; Mckibben, B.; Gardener, N.; Rivers, T.; Nottingham, G.; Golden, B.; Barfield, B.; Bruening, J.; Wood, D.

1992-01-01

282

Orbital Debris Studies at NASA  

NASA Technical Reports Server (NTRS)

Any discussion of expanding the capabilities of Space Surveillance Networks to include tracking and cataloging smaller objects will require a good understanding of orbital debris. In the current U.S. catalog of over 11,000 objects, more than 50% are classified as "debris" to include fragmentation debris, operational debris, liquid metal coolant, and Westford needles. If the catalog is increased to 100,000 objects by lowering the tracked object size threshold, almost all of the additional objects will be orbital debris. The Orbital Debris Program Office has been characterizing the small orbital debris environment through measurements and modeling for many years. This presentation will specifically discuss two different studies conducted at NASA. The first study was done in 1992 and examined the requirements and produced a conceptual design for a Collision Avoidance Network to protect the Space Station Freedom from centimeter sized orbital debris while minimizing maneuvers. The second study was conducted last year and produced NASA s estimate of the orbital population for the years 2015 and 2030 for objects 2 cm and larger.

Stansbery, Gene; Krisko, Paula; Whitlock, Dave

2007-01-01

283

Satellite Orbital Interpolation Comparison Methods  

NASA Astrophysics Data System (ADS)

A satellite or artificial probe orbit is made of time series of orbital elements such as state vectors (position and velocities, keplerian orbital elements) given at regular or irregular time intervals. These time series are fitted to observations, so that differences between observations (distance, radial velocity) and the theoretical quantity be minimal, according to a statistical criterion, mostly based on the least-squared algorithm. These computations are carried out using dedicated software, such as the GINS used by GRGS, mainly at CNES Toulouse and Paris Observatory. From an operational point of view, time series of orbital elements are 7-day long. Depending on the dynamical configurations, more generally, they can typically vary from a couple of days to some weeks. One of the fundamental parameters to be adjusted is the initial state vector. This can lead to time gaps, at the level of a few dozen of centimeters between the last point of a time series to the first one of the following data set. The objective of this presentation consists in the improvement of an interpolation method freed itself of such possible "discontinuities" resulting between satellite's orbit arcs when a new initial bulletin is adjusted. We show the principles of interpolation for these time series and compare solutions coming from different interpolation methods such as Lagrange polynomial, spline cubic, Chebyshev orthogonal polynomial and cubic Hermite polynomial. These polynomial coefficients are used to reconstruct and interpolate the satellite orbits without time gaps and discontinuities and requiring a weak memory size.

Richard, J.-Y.; Deleflie, F.; Gambis, D.

2012-04-01

284

Laser Ranging to Lunar Reconnaissance Orbiter: time, orbit, and beyond  

NASA Astrophysics Data System (ADS)

Since the commissioning of the Lunar Reconnaissance Orbiter (LRO) in June, 2009, one-way laser ranging (LR) to LRO has been conducted regularly from NASA's Next Generation Satellite Laser Ranging System (NGSLR) at Goddard Geophysical and Astronomical observatory (GGAO) in Greenbelt, Maryland. With the support of the International Laser Ranging Service (ILRS), ten international satellite laser ranging (SLR) ground stations have participated in this experiment and over 1200 hours of ranging data have been collected. The one-way range measurements have been used to study the long term behavior of the LRO clock and to aid in the precision orbit determination (POD) of LRO. In December 2011, LRO moved to an eccentric orbit from its previous near-circular orbit. LR data showed that both the frequency and the drift rate of the clock oscillator have changed significantly after transition to the eccentric orbit, resulting in increased residuals. Despite this change of characteristics of the LRO clock, the oscillator has been very stable over the last 3 years. Thus, for our POD processing with both LR and Universal Space Network (USN) data, we first estimate the LRO clock parameters over a long time period, which reduces their dependence on specific LR ground station clock performance. This separation of the spacecraft and ground station clocks can further strengthen the constraints LR data place on the orbital solutions. In addition to the nominal one-way ranging to LRO, LR stations have performed in 2012 a series of time transfer and laser communication experiments using LRO as a terminal in space. At present, the time transfer accuracy is within 15 ns between the two laser stations at Goddard Space Flight Center in Greenbelt, Maryland. In the laser communication experiments, images have been successfully transmitted from NGSLR and received by LRO. We present results from these experiments and orbital solutions using LR data.

Mao, D.; Mcgarry, J.; Sun, X.; Torrence, M. H.; Hoffman, E.; Skillman, D.; Rowlands, D. D.; Mazarico, E.; Golder, J.; Neumann, G. A.; Barker, M. K.; Zuber, M. T.; Smith, D. E.

2012-12-01

285

Precision Orbit Determination for the Lunar Reconnaissance Orbiter  

NASA Astrophysics Data System (ADS)

The U.S. Lunar Reconnaissance Orbiter (LRO) mission will be launched in October 2008, and will carry out a detailed mapping of the Moon using a science payload of multiple instruments, including the Lunar Orbiter Laser Altimeter (LOLA), and the Lunar Reconnaissance Orbiter Camera (LROC) (Chin, 2007). One of the primary goals of the LRO mission is develop a geodetic grid for the planet. A subsidiary goal is the improvement of the lunar gravity field. The environment for POD on LRO is especially challenging. The spacecraft will orbit the Moon at a mean altitude of 50 km, and the expected error from the Lunar Prospector series of gravity models (to degree 100 or to degree 150) can be expected to be hundreds of meters. LRO will be tracked by S Band Doppler from White Sands, New Mexico, and Dongara, Australia, as well as by one-way laser ranging from Satellite Laser Ranging (SLR) tracking stations on the Earth. However, unlike the Japanese lunar mission SELENE (Kaguya), no direct tracking will be available while the spacecraft is over the lunar farside. We review the status of orbit modelling for LRO, for both the geopotential modelling and the nonconservative force models, as well as anticipated improvements. We discuss the modelling for the one-way laser ranging observable, and how the data from the one-way laser ranging (LR) system will be acquired from selected stations of the global stations of the SLR network. We discuss the orbit determination strategies which we expect to implement on this mission, including the use of altimeter crossovers from the LOLA instrument to supplement the Earth-based tracking and we review the projected orbit determination accuracies that will be attainable.

Lemoine, Frank; Rowlands, David; McGarry, Jan; Neumann, Gregory; Chinn, Douglas; Mazarico, Erwan; Torrence, Mark

286

Space Tourism: Orbital Debris Considerations  

NASA Astrophysics Data System (ADS)

Space activities after a phase of research and development, political competition and national prestige have entered an era of real commercialization. Remote sensing, earth observation, and communication are among the areas in which this growing industry is facing competition and declining government money. A project like International Space Station, which draws from public money, has not only opened a window of real multinational cooperation, but also changed space travel from a mere fantasy into a real world activity. Besides research activities for sending man to moon and Mars and other outer planets, space travel has attracted a considerable attention in recent years in the form of space tourism. Four countries from space fairing nations are actively involved in the development of space tourism. Even, nations which are either in early stages of space technology development or just beginning their space activities, have high ambitions in this area. This is worth noting considering their limited resources. At present, trips to space are available, but limited and expensive. To move beyond this point to generally available trips to orbit and week long stays in LEO, in orbital hotels, some of the required basic transportations, living requirements, and technological developments required for long stay in orbit are already underway. For tourism to develop to a real everyday business, not only the price has to come down to meaningful levels, but also safety considerations should be fully developed to attract travelers' trust. A serious hazard to space activities in general and space tourism in particular is space debris in earth orbit. Orbiting debris are man-made objects left over by space operations, hazardous to space missions. Since the higher density of debris population occurs in low earth orbit, which is also the same orbit of interest to space tourism, a careful attention should be paid to the effect of debris on tourism activities. In this study, after a review of the current work on space tourism and debris situation in low earth orbit suitable orbits for space tourism activities with regard to the presence of orbital debris are discussed.

Mahmoudian, N.; Shajiee, S.; Moghani, T.; Bahrami, M.

2002-01-01

287

A criterion to classify asteroids and comets based on the orbital parameters  

NASA Astrophysics Data System (ADS)

The classification criterion between asteroids and comets has evolved in recent decades, but the main distinction remains unchanged. Comets present gas and dust ejection from the surface at some point of their orbits, therefore, these objects are considered to be active. On the other hand, asteroids do not show any kind of large scale gas and dust ejection, they are inert. Nevertheless, this classification scheme is impractical when we have more than 500,000 asteroids already discovered. In addition, comets are not active all along their orbits. In order for a comet to display activity at present or in the recent past in the inner region of the Solar System (heliocentric distance <2 AU), the cometary orbit must be unstable in the time scale on the order of ten thousands of years; otherwise, the object should have completely consumed its volatile component. Close encounters with the most massive planets is the only mechanism that could produce “macroscopic” instabilities on a short time scale. The macroscopic changes in the orbital elements can be detected in a numerical integration of the dynamical evolution of the object over a time scale of several thousand years. This procedure to identify asteroids in cometary-like orbits is also impractical because it would require months of computing time. Therefore, a classification scheme based on the orbital elements to identify the border cases between the asteroid and comet populations is urgently required. We present a criterion to classify asteroids and comets and to find the border case based on the Tisserand’s parameter, the Minimum Orbital Intersection Distance (MOID), and considering some information regarding the aphelion and perihelion distances. Objects in mean-motion are disregarded. After applying a filter to the sample of over half a million asteroids already discovered to select the precise orbits and to the sample of 487 short-period comets, we apply the proposed classification criterion. The resulting sample consists of ?331 Asteroids in Cometary Orbits (ACOs). The ACOs are further classified in subclasses similar to the cometary classification. There are 436 Jupiter Family Comets and 203 ACOs of the Jupiter Family type. This new criterion is more strict that the criteria used by other authors to identify ACOs; nonetheless, with the new criterion we ensure that the ACOs have a chaotic dynamical evolution similar to the periodic comets. The discovered dormant or extinct comets seems, if they exist at all, to be a small fraction of the active comets. We also analyse the available photometric data of ACOs to identify possible large brightness variations. Among the sample of ACOs, there is only one object with brightness variations typical of an active comet: 174P/(60558) Echeclus. But this object has already been double classified as asteroid and comet.

Tancredi, Gonzalo

2014-05-01

288

An Analytical Satellite Orbit Predictor (ASOP)  

NASA Technical Reports Server (NTRS)

The documentation and user's guide for the Analytical Satellite Orbit Predictor (ASOP) computer program is presented. The ASOP is based on mathematical methods that represent a new state-of-the-art for rapid orbit computation techniques. It is intended to be used for computation of near-earth orbits including those of the shuttle/orbiter and its payloads.

Starke, S. E.

1977-01-01

289

Elementary Analysis of Translunar Apollo Orbit  

Microsoft Academic Search

Geometrical parameters of the translunar Apollo orbit are derived from elementary equations relating to elliptical and hyperbolic orbits in an inverse-square force field. The simplification is to divide the problem into an elliptical orbit in the region where the earth's attraction dominates and a hyperbolic orbit (referred to a moving coordinate system attached to the moon) in the region where

R. W. Christy; M. R. Mayhugh

1969-01-01

290

Tribochemistry of ZDDP in molecular orbital calculations  

Microsoft Academic Search

The molecular orbital parameters of zinc dialkyldithiophosphate (ZDDP) and several metal-atom-cluster models were calculated. The nature and the strength of the interactions between the ZDDP molecules and different metal surfaces are analysed and discussed with the use of frontier orbital theory. By comparing the highest occupied molecular orbital energy (EHOMO) and the lowest unoccupied molecular orbital energy (ELUMO) of the

Yuanqiang Tan; Weijiu Huang; Xueye Wang

2004-01-01

291

Quasihalo Orbits Associated With Libration Points  

Microsoft Academic Search

Quasihalo orbits are Lissajous trajectories librating about the well known halo orbits. Themain feature of these orbits is that they keep an exclusion zone in the same way that haloorbits do. As a result, the knowledge of this type of orbit, gives more flexibility to the missionanalysis design about collinear libration points of any pair of primaries in the solar

Gerard Gomez; Josep Masdemont; Carles Simo

1998-01-01

292

Pseudotumor of the orbit in early childhood  

Microsoft Academic Search

Orbital pseudotumor, also known as idiopathic orbital inflammation, is defined as a nonspecific, nonneoplastic inflammatory process of the orbit without identifiable local or systemic causes. The disorder, first described by Birch-Hirschfield in 1905,1 is more prevalent in the adult population than in the pediatric population. In our study we discuss two cases of pseudotumor of the orbit in children less

Julia L. Stevens; Paul J. Rychwalski; Robert S. Baker; Richard S. Kielar

1998-01-01

293

Orbit Evolution in Common Envelopes  

NASA Astrophysics Data System (ADS)

We study how the inclination angle and eccentricity evolve during a common envelope phase. During a common envelope phase, a compact star is swallowed by its giant companion and spirals into a tighter orbit. A close binary results if the compact star releases enough energy to expel the envelope. We investigate possible fossil evidence of the common envelope phase on the inclination angle and the eccentricity. A convective common envelope leads to force component perpendicular to the orbital plane, and thus change the orbital inclination. This makes it harder to uniquely identify the signature of neutron star natal kicks. A common envelope is usually assumed to circularize orbits, but some eccentricity in fact arises both from the spiral-in process itself, and from random forces in the orbital plane. When the envelope is expelled, it might seem that the binary system would preserve whatever eccentricity had been established at the final stage of the inspiral. But tidal dissipation by the residual envelope can reduce the eccentricity. The final eccentricity depends on which of these effects wins or how they balance each other. We discuss applications and observational tests of these predictions.

Luan, Jing; Phinney, E. S.

2011-09-01

294

Champ precise orbit determination using GPS data  

Microsoft Academic Search

Precise CHAMP orbits have been computed in the framework of the IGS\\/LEO CHAMP Orbit Comparison Campaign for a period of 11 days in May 2001. A reduced-dynamic orbit determination strategy has been applied based on ionospheric-free triple-differenced GPS phase measurements along with precise GPS orbits computed by the International GPS Service (IGS). The resulting CHAMP orbit accuracy is assessed using

J. van den Ijssel; P Visser; E Patiño Rodriguez

2003-01-01

295

Radio frequency interference at the geostationary orbit  

NASA Technical Reports Server (NTRS)

Growing demands on the frequency spectrum have increased the possibility of radio frequency interference (RFI). Various approaches to obtain in orbit RFI data are compared; this comparision indicates that the most practical way to obtain RFI data for a desired orbit (such as a geostationary orbit) is through the extrapolation of in orbit RFI measurements by a low orbit satellite. It is concluded that a coherent RFI program that uses both experimental data and analytical predictions provides accurate RFI data at minimal cost.

Sue, M. K.

1981-01-01

296

The Brauer loop scheme and orbital varieties  

NASA Astrophysics Data System (ADS)

A. Joseph invented multidegrees in Joseph (1984) to study orbital varieties, which are the components of an orbital scheme, itself constructed by intersecting a nilpotent orbit with a Borel subalgebra. Their multidegrees are known as Joseph polynomials, and these polynomials give a basis of a (Springer) representation of the Weyl group. In the case of the nilpotent orbit {M2=0}, the orbital varieties can be indexed by noncrossing chord diagrams in the disk.

Knutson, Allen; Zinn-Justin, Paul

2014-04-01

297

Orbital-only models: ordering and excitations  

Microsoft Academic Search

We consider orbital-only models in Mott insulators, where the orbital–orbital interactions are either due to Jahn–Teller distortions or due to the Kugel–Khomskii superexchange. This leads to highly anisotropic and frustrated orbital Hamiltonians. For two-fold degenerate eg systems, both types of orbital interactions lead to the same form of the Hamiltonian—the 120° model. In both cases, the predicted symmetry of the

Jeroen van den Brink

2004-01-01

298

The Challenge of Orbital Debris  

NASA Technical Reports Server (NTRS)

Since the dawn of the Space Age more than 50 years ago, humans have been launching objects into the space environment faster than they have been removed by active means or natural decay. This has led to a proliferation of debris -- derelict satellites, discarded rocket upper stages, and pieces from satellite breakups -- in Earth orbit, especially in well-used orbital regimes. This talk will summarize the current knowledge of the debris environment and describe plans to address the challenges orbital debris raises for the future usability of near-Earth space. The talk will be structured around 4 categories: Measurements, Modeling, Shielding, and Mitigation. This will include discussions of the long-term prognosis of debris growth (i.e., the "Kessler Syndrome") as well as plans for active debris removal.

Matney, Mark

2012-01-01

299

Orbital, Rotational, and Climatic Interactions  

SciTech Connect

The report of an international meeting on the topic of Orbital, Rotational, and Climatic Interactions, which was held 9-11 Jul. 1991 at the Johns Hopkins University is presented. The meeting was attended by 22 researchers working on various aspects of orbital and rotational dynamics, paleoclimate data analysis and modeling, solid-Earth deformation studies, and paleomagnetic analyses. The primary objective of the workshop was to arrive at a better understanding of the interactions between the orbital, rotational, and climatic variations of the Earth. This report contains a brief introduction and 14 contributed papers which cover most of the topics discussed at the meeting. Separate abstracts have been prepared for articles from this report.

Bills, B.G.

1992-12-01

300

Management of the orbital environment  

NASA Technical Reports Server (NTRS)

Data regarding orbital debris are presented to shed light on the requirements of environmental management in space, and strategies are given for active intervention and operational strategies. Debris are generated by inadvertent explosions of upper stages, intentional military explosions, and collisional breakups. Design and operation practices are set forth for minimizing debris generation and removing useless debris from orbit in the low-earth and geosynchronous orbits. Self-disposal options include propulsive maneuvers, drag-augmentation devices, and tether systems, and the drag devices are described as simple and passive. Active retrieval and disposition are considered, and the difficulty is examined of removing small debris. Active intervention techniques are required since pollution prevention is more effective than remediation for the problems of both earth and space.

Loftus, Joseph P., Jr.; Kessler, Donald J.; Anz-Meador, Phillip D.

1991-01-01

301

Orbital involvement in systemic mastocytosis.  

PubMed

Abstract A 61-year-old female presented with a 3-day history of painful and reddened right eye with painful ocular movements. She had been diagnosed as having systemic mastocytosis 4 years earlier. Ocular examination showed Best Corrected Visual acuity of 6/6 right eye and 6/6 left eye. There was marked conjunctival injection and chemosis. The posterior segment was normal. The left eye was normal. Exophthalmometry showed 2?mm of right proptosis relative to the left eye. Computed tomography (CT) scans showed an ill-defined intra-conal lesion and enlargement of the lacrimal gland in the right orbit. A diagnostic biopsy was performed; the histopathology findings were of orbital mastocytosis. We present what our literature search suggests is the first biopsy-proven case of orbital mastocytosis. PMID:24410676

Meena, Manju; Benger, Ross; Karnaukhvoa, Irina; Waring, Dale; Li, Yi-Chiao

2014-06-01

302

Orbiter Atlantis returns to KSC  

NASA Technical Reports Server (NTRS)

Stairs are rolled to the forward opening of the Shuttle Carrier Aircraft -- with its piggyback cargo, the orbiter Atlantis -- after it rolls to a stop at the Shuttle Landing Facility. Atlantis returns home after a 10-month stay in the Palmdale, CA, orbiter processing facility undergoing extensive inspections and modifications. They included several upgrades enabling it to support International Space Station missions, such as adding an external airlock for ISS docking missions and installing thinner, lighter thermal protection blankets for weight reduction which will allow it to haul heavier cargo. The flight from Palmdale included a fueling stop in Ft. Hood, TX, and overnight stay at Ft. Campbell, KY. Atlantis will undergo preparations in the Orbiter Processing Facility at KSC for its planned flight in June 1999.

1998-01-01

303

Orbiter Atlantis returns to KSC  

NASA Technical Reports Server (NTRS)

The Shuttle Carrier Aircraft rolls to a stop with its piggyback cargo -- orbiter Atlantis -- at the Shuttle Landing Facility. In the background is the Vehicle Assembly Building. Atlantis returns home after a 10-month stay in the Palmdale, CA, orbiter processing facility undergoing extensive inspections and modifications. They included several upgrades enabling it to support International Space Station missions, such as adding an external airlock for ISS docking missions and installing thinner, lighter thermal protection blankets for weight reduction which will allow it to haul heavier cargo. The flight from Palmdale included a fueling stop in Ft. Hood, TX, and overnight stay at Ft. Campbell, KY. Atlantis will undergo preparations in the Orbiter Processing Facility at KSC for its planned flight in June 1999.

1998-01-01

304

[Inflammatory diseases of the orbit].  

PubMed

Inflammatory conditions belong to the most important diseases of the orbit. Children and adolescents are mostly affected and the most common cause is secondary pathogen invasion from acute sinusitis. However in adults most cases involve idiopathic orbital inflammation, previously termed pseudotumor orbitae. Clinical presentation may include painful exophthalmus, skin redness and warming, chemosis and disturbed eye motility. The challenge for imaging investigations, mainly a combination of CT scanning and MRI, is to distinguish inflammatory from malignant conditions, to define the extent of lesions and to document possible complications, such as cavernous sinus thrombosis, meningoencephalitis or cerebral abscesses. Serious potential consequences of orbital infections, including loss of vision or death, are still a risk factor and must be averted by avoidance of delays in diagnosis and appropriate clinical management. PMID:19002425

Zimmer, A; Reith, W

2008-12-01

305

Orbit and properties of the massive X-ray binary BD +60 73=IGR J00370+6122  

NASA Astrophysics Data System (ADS)

Context. High-energy X-rays generated in massive binary systems can arise from several different mechanisms. Constraints on the orbital parameters of these systems are therefore necessary to properly understand and interpret the X-ray phenomena. Aims: In this study we aim to determine a spectroscopic orbit for the high-mass X-ray binary system BD +60 73=IGR J00370+6122, to infer the properties of the optical and compact companion, and to interpret the characteristics of the X-ray light curve within the context of our findings. Methods: We acquired 123 spectroscopic observations with the David Dunlap Observatory and Kitt Peak National Observatory telescopes in the optical domain. Using a cross-correlation technique, we measured the radial velocity of each of these spectra relative to the heliocentric rest-frame. An orbital solution was obtained from the resulting radial velocity measurements. Spectra of several spectral standards were also acquired to reassess the spectral classification of the optical companion. Results: The best-fit orbital parameters suggest an eccentricity of e = 0.48+0.02-0.03 and a mass-function of f(M) = 0.009 ± 0.002, lending further support to the assumption that the companion is a low-mass compact star. We find that the X-ray maximum occurs just after the time of periastron passage, but before the time of superior conjunction when the optical companion could eclipse the compact companion. The spectrum of the optical companion is best matched by the B1Ib spectral standard HD 24398, which reaffirms the original classification. Conclusions: The mass-function combined with a plausible range of possible masses for a neutron star companion yields primary masses within the range expected for the spectral type of BD +60 73 for high orbital inclinations. The compact companion cannot be a black hole unless the supergiant has an exceptionally high mass for its B1Ib spectral type or if the inclination of its orbit is very low. The X-ray timing and characteristics can potentially be explained by accretion variations on the compact object; but this would require the companion to be a magnetar. Table 2 is available in electronic form at http://www.aanda.org

Grunhut, J. H.; Bolton, C. T.; McSwain, M. V.

2014-03-01

306

Stable orbit rendezvous for a small radius translunar halo orbit  

Microsoft Academic Search

A two spacecraft terminal phase rendezvous targeting law, which is valid for the three-body problem, is given. The relevant equations of motion are derived and the targeting law developed assuming the traditional target\\/chaser vehicle relationship. The targeting law is demonstrated using a small radius translunar halo orbit. Nonlinear simulation results verify that acceptable performance is obtained. Using these results, the

Brian L. Jones; Robert H. Bishop

1993-01-01

307

Comet Halley - The orbital motion  

NASA Technical Reports Server (NTRS)

The orbital motion of Comet Halley is investigated over the interval from A.D. 837 to 2061. Using the observations from 1607 through 1911, least-squares differential orbit corrections were successfully computed using the existing model for the nongravitational forces. The nongravitational-force model was found to be consistent with the outgassing-rocket effect of a water-ice cometary nucleus and, prior to the 1910 return, these forces are time-independent for nearly a millennium. For the 1986 return, viewing conditions are outlined for the comet and the related Orionid and Eta Aquarid meteor showers.

Yeomans, D. K.

1977-01-01

308

Epithelioid sarcoma of the orbit  

PubMed Central

Epithelioid sarcoma is an aggressive and rare malignancy first recognized by Enzinger in 1970. It is known most commonly to affect the distal upper extremities in young adults. The classical “distal” form has a male predominance and can also involve other less frequent sites including lower extremities, proximal upper extremities, and the trunk. The “proximal” variant of this tumor is deep seated, tends to occur in older patients and predominantly develops in the pelvis, perineum, and genital tract. In the orbit, only a single report of two cases, which had a typical histopathologic appearance, has been previously published. We present the third case of orbital primary epithelioid sarcoma.

Alkatan, Hind M.; Chaudhry, Imtiaz; Al-Qahtani, Abdullah

2011-01-01

309

Orbiter electrical equipment utilization baseline  

NASA Technical Reports Server (NTRS)

The baseline for utilization of Orbiter electrical equipment in both electrical and Environmental Control and Life Support System (ECLSS) thermal analyses is established. It is a composite catalog of Space Shuttle equipment, as defined in the Shuttle Operational Data Book. The major functions and expected usage of each component type are described. Functional descriptions are designed to provide a fundamental understanding of the Orbiter electrical equipment, to insure correlation of equipment usage within nominal analyses, and to aid analysts in the formulation of off-nominal, contingency analyses.

1980-01-01

310

Simulating Orbital Operations Of Spacecraft  

NASA Technical Reports Server (NTRS)

Orbital Operations Simulator, OOS, computer program developed to implement mathematical models of complex outer-space vehicular systems and be "testbed" for new flight software. Has multi-vehicular-simulation capability to model on-orbit proximity and docking operations. Version 1.0, with its Prepare Processor and User Interface Shell designed to be true multivehicle dynamic simulator with capability to change mathematical models of spacecraft subsystems easily. Written in K & R standard C, LEX, and YACC languages and operates under System V shell.

Edwards, Carter; Bailey, Robert W.

1993-01-01

311

Frequentist confidence intervals for orbits  

NASA Astrophysics Data System (ADS)

The problem of efficiently computing the orbital elements of a visual binary while still deriving confidence intervals with frequentist properties is treated. When formulated in terms of the Thiele-Innes elements, the known distribution of probability in Thiele-Innes space allows efficient grid-search plus Monte-Carlo-sampling schemes to be constructed for both the minimum-?2 and the Bayesian approaches to parameter estimation. Numerical experiments with 104 independent realizations of an observed orbit confirm that the 1 - and 2? confidence and credibility intervals have coverage fractions close to their frequentist values. Appendix is available in electronic form at http://www.aanda.org

Lucy, L. B.

2014-05-01

312

Orbital effects in actinide systems  

SciTech Connect

Actinide magnetism presents a number of important challenges; in particular, the proximity of 5f band to the Fermi energy gives rise to strong interaction with both d and s like conduction electrons, and the extended nature of the 5f electrons means that they can interact with electron orbitals from neighboring atoms. Theory has recently addressed these problems. Often neglected, however, is the overwhelming evidence for large orbital contributions to the magnetic properties of actinides. Some experimental evidence for these effects are presented briefly in this paper. They point, clearly incorrectly, to a very localized picture for the 5f electrons. This dichotomy only enhances the nature of the challenge.

Lander, G.H.

1983-01-01

313

Orbital dynamics in galaxy mergers  

NASA Astrophysics Data System (ADS)

In the favored vacuum energy + cold dark matter (ACDM) cosmology, galaxies form through a hierarchical merging process. Mergers between comparable-mass sys tems are qualitatively different from the ongoing accretion of small objects by much larger ones, in that they can radically transform the nature of the merging objects, e.g. through violent relaxation of the stars and dark matter, triggered starbursts, and quasar activity. This thesis covers two phenomena unique to major galaxy mergers: the formation of supermassive black hole (SMBH) binary and triple systems, and the transformation of the stellar orbit structure through violent relaxation, triggered gas inflow, and star formation. In a major merger, the SMBHs can spiral in and form a bound binary in less than a Hubble time. If the binary lifetime exceeds the typical time between mergers, then triple black hole (BH) systems may form. We study the statistics of close triple-SMBH encounters in galactic nuclei by computing a series of three-body orbits with physically-motivated initial conditions appropriate for giant elliptical galaxies. Our simulations include a smooth background potential consisting of a stellar bulge plus a dark matter halo, drag forces due to gravitational radiation and dynamical friction on the stars and dark matter, and a simple model of the time evolution of the inner density profile under heating and mass ejection by the SMBHs. We find that the binary pair coalesces as a result of repeated close encounters in ~85% of our runs. In about 40% of the runs the lightest BH is left wandering through the galactic halo or escapes the galaxy altogether. The triple systems typically scour out cores with mass deficits ~1-2 times their total mass. The high coalescence rate and prevalence of very high-eccentricity orbits could provide interesting signals for the future Laser Interferometer Space Antenna (LISA). Our study of remnant orbit structure involved 42 disk-disk mergers at various gas fractions, and 10 re-mergers of the 40% gas remnants. All simulations were run using a version of GADGET-2 [173] that included subresolution models of radiative cooling, star formation, and supernova and AGN feedback. The potential was frozen at the last snapshot of each simulation and the orbits of ~50,000 randomly chosen stars were integrated for ~100 dynamical times, and classified based on their Fourier spectra using the algorithm of [30]. The 40% gas remnants were found to be dominated by minor-axis tube orbits in their inner regions, whereas box orbits were the dominant orbit family in the inner parts of the dissipationless disk-disk and remnant-remnant systems. The phase space available to minor-axis tube orbits in even the 5% gas remnants was much larger than that in the dissipationless remnants, but the 5% gas remnants are not fast rotators because these orbits tend to be isotropically distributed at low gas fractions. Some of the remnants show significant minor axis rotation, due to large orientation twists in their outer parts (in the 40% gas remnants) and asymmetrically rotating major-axis tube orbits throughout the remnants (in the re-mergers).

Hoffman, Loren

314

Improving the orbit estimates of GPS satellites.  

NASA Astrophysics Data System (ADS)

The extended Center for Orbit Determination in Europe (CODE) orbit model, an empirical orbit model proposed by Beutler and colleagues in 1994, has been tested extensively since January 1996. Apart from six osculating Keplerian elements, this orbit model consists of nine (instead of the conventional two) parameters to take into account the deterministic part of the force field acting on the satellites. Based on the test results an improved orbit parameterization is proposed. The new orbit parameterization consists of the conventional two parameters plus three additional parameters, a constant and two periodic terms (a cosine and a sine term), in the X-direction to model the effects of the solar radiation pressure. Results based on one full year of routine orbit estimation, using the original and the new orbit parameterization, are presented to demonstrate the superiority of the new approach. An improvement of the orbit estimates with at least a factor of two is observed.

Springer, T. A.; Beutler, G.; Rothacher, M.

1999-04-01

315

Otolaryngologists and orbital pseudotumor: a case report.  

PubMed

Orbital pseudotumor (idiopathic orbital inflammation) is the third most common orbital disease, accounting for 5 to 6% of orbital disorders. It often presents in a manner very similar to inflammatory or neoplastic sinus disease. In addition, sinus disease is often a cause of orbital pseudotumor, although the etiology of this entity has yet to be defined. Treatment with steroids is usually successful early on, but long-term treatment-failure and recurrence rates are high. Despite otolaryngologists' intimate knowledge of sinus pathology, we have generally not been heavily involved in researching the causes and treatment of orbital pseudotumors. In this article, we report the case of an affected patient who presented with an orbital mass on radiography. The mass was likely the result of sinus disease in the setting of an untreated orbital floor fracture. We describe the clinical, radiographic, and operative features of this case, and we discuss the otolaryngologist's role in the management of orbital pseudotumors. PMID:18833526

Mehta, Vikas; Torkian, Behrooz A; Daines, Steven M; Kelly, Timothy F

2008-10-01

316

Getting a Crew into Orbit  

ERIC Educational Resources Information Center

Despite the temporary setback in our country's crewed space exploration program, there will continue to be missions requiring crews to orbit Earth and beyond. Under the NASA Authorization Act of 2010, NASA should have its own heavy launch rocket and crew vehicle developed by 2016. Private companies will continue to explore space, as well. At the…

Riddle, Bob

2011-01-01

317

Variational definitions of orbital energies  

NASA Astrophysics Data System (ADS)

A formulation of Koopmans' theorem is derived for high-spin half-filled open shells in the restricted openshell Hartree-Fock (ROHF) method based on a variational treatment of both the initial (non-ionized) open-shell system X with spin S and the corresponding ions having a hole or an extra electron in the closed, open and virtual shells respectively. The six processes for forming ions with spin S+/-1/2 require two different definitions for canonical orbitals within each shell. These processes may be treated equivalently within a restricted CI using arbitrary non-canonical linear transforms of the ROHF orbitals optimal for the initial system. Canonical UHF orbitals also obey a variational principle for the ion energies, but they provide less appropriate estimates for actual states of the ion. Canonical spin-unrestricted Kohn-Sham orbitals with common exchange-correlation functionals suffer from all of the UHF problems and from selfinteraction error. They generally are not useful estimates for ion energies.

Davidson, Ernest R.

2012-12-01

318

Analytic theory of orbit contraction  

Microsoft Academic Search

The motion of a satellite in orbit, subject to atmospheric force and the motion of a reentry vehicle are governed by gravitational and aerodynamic forces. This suggests the derivation of a uniform set of equations applicable to both cases. For the case of satellite motion, by a proper transformation and by the method of averaging, a technique appropriate for long

N. X. Vinh; J. M. Longuski; A. Busemann; R. D. Culp

1977-01-01

319

Viking orbiter stereo imaging catalog  

NASA Technical Reports Server (NTRS)

The extremely long mission of the two Viking Orbiter spacecraft produced a wealth of photos of surface features. Many of these photos can be used to form stereo images allowing the student of Mars to examine a subject in three dimensional. This catalog is a technical guide to the use of stereo coverage within the complex Viking imaging data set.

Blasius, K. R.; Vertrone, A. V.; Lewis, B. H.; Martin, M. D.

1982-01-01

320

Orbits Within Spherical Galaxies Model  

NSDL National Science Digital Library

The Orbits Within Spherical Galaxies model displays the two-dimensional trajectories of particles (stars) within a galaxy having a spherically symmetric mass distribution that heuristically approximates the distributions found in galaxies and bulges. The model uses a mass density proposed by Walter Dehnen to describe spatial distributions that vary as râ»â´ and râ»g in galactic envelopes and cores where g is an adjustable power-law parameter. Units are chosen such that a typical galaxy has total mass M=1 and that the gravitational constant G=1. The Orbits Within Spherical Galaxies model is a supplemental simulation for the article "Radial motion in a central potential for singular mass densities" by Ulrich Zürcher and Miron Kaufman in the American Journal of Physics 79(5), 521-526 (2011) and has been approved by the authors and the American Journal of Physics (AJP) editor. The simulation was developed using the Easy Java Simulations (EJS) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_mech_orbits_OrbitsWithinSphericalGalaxies.jar file will run the program if Java is installed.

Christian, Wolfgang

2011-01-12

321

Orbiter thermal control subsystem development  

NASA Technical Reports Server (NTRS)

Selected major hardware components and subsystems of the shuttle orbiter are described. These include the hardware configurations, development problems and solutions, performance requirements and attainment, major hardware fabrication problems and solutions, development test objectives and implementation, and utilization of test results for hardware refinements. The subsystems selected for discussion are the space radiator, the ammonia boiler, the flash evaporator, and avionics cold plates.

Laubach, G. E.

1978-01-01

322

Orbits in Strongly Curved Spacetime  

NSDL National Science Digital Library

This applet shows from three different physical perspectives the orbit of a low-mass test particle around a non-rotating black hole. Below the applet is an instructional guide to the applet and a description of the parameters involved.

Walker, John

2010-01-27

323

Non-infectious orbital vasculitides  

PubMed Central

Non-infectious vasculitides comprise a large number of diseases. Many of these diseases can cause inflammation within the orbit and a clinical presentation, which mimics numerous other processes. Orbital disease can often be the initial presentation of a systemic process and early diagnosis can help prevent long-term, potentially fatal consequences. The evaluation and treatment of non-infectious orbital vasculitides are often complicated and require a thorough understanding of the disease and underlying systemic associations. The long-term prognosis visually and systemically must be weighed against the risks and benefits of the treatment regimen. A large variety of corticosteroid formulations currently exist and are the mainstay of initial treatment. Traditional steroid-sparing immunosuppressive agents are also an important arsenal against these vasculitides. Recently, a new class of drugs called biologics, which target the various mediators of the inflammation cascade, may potentially provide more effective and less toxic treatment. This review aims to synthesize the current literature on non-infectious orbital vasculitides.

Perumal, B; Black, E H; Levin, F; Servat, J J

2012-01-01

324

Launching Social Studies into Orbit.  

ERIC Educational Resources Information Center

As a social studies educator, Christa McAuliffe was delighted that a "non-science teacher" was chosen to become the first teacher to orbit the earth. Her thoughts concerning the NASA space flight and its meaning for the social studies are discussed. (RM)

Stone, Kirk

1986-01-01

325

Gravitational Orbits and Space Flight  

NSDL National Science Digital Library

These lecture notes discuss Newton's theories of dynamics and gravity. The various kinds of possible orbits are described in this lecture. The evolution of space technology such as rockets, the Space Shuttle, dozens of robot spacecraft, and the human space program are also discussed.

O'Connell, Robert

2005-06-28

326

Space Shuttle Orbiter-Illustration  

NASA Technical Reports Server (NTRS)

This illustration is an orbiter cutaway view with callouts. The orbiter is both the brains and heart of the Space Transportation System (STS). About the same size and weight as a DC-9 aircraft, the orbiter contains the pressurized crew compartment (which can normally carry up to seven crew members), the huge cargo bay, and the three main engines mounted on its aft end. There are three levels to the crew cabin. Uppermost is the flight deck where the commander and the pilot control the mission. The middeck is where the gallery, toilet, sleep stations, and storage and experiment lockers are found for the basic needs of weightless daily living. Also located in the middeck is the airlock hatch into the cargo bay and space beyond. It is through this hatch and airlock that astronauts go to don their spacesuits and marned maneuvering units in preparation for extravehicular activities, more popularly known as spacewalks. The Space Shuttle's cargo bay is adaptable to hundreds of tasks. Large enough to accommodate a tour bus (60 x 15 feet or 18.3 x 4.6 meters), the cargo bay carries satellites, spacecraft, and spacelab scientific laboratories to and from Earth orbit. It is also a work station for astronauts to repair satellites, a foundation from which to erect space structures, and a hold for retrieved satellites to be returned to Earth. Thermal tile insulation and blankets (also known as the thermal protection system or TPS) cover the underbelly, bottom of the wings, and other heat-bearing surfaces of the orbiter to protect it during its fiery reentry into the Earth's atmosphere. The Shuttle's 24,000 individual tiles are made primarily of pure-sand silicate fibers, mixed with a ceramic binder. The solid rocket boosters (SRB's) are designed as an in-house Marshall Space Flight Center project, with United Space Boosters as the assembly and refurbishment contractor. The solid rocket motor (SRM) is provided by the Morton Thiokol Corporation.

2001-01-01

327

Orbital Debris Research at NASA  

NASA Technical Reports Server (NTRS)

The United States has one of the most active programs of research of the orbital debris environment in the world. Much of the research is conducted by NASA s Orbital Debris Program Office at the Johnson Space Center. Past work by NASA has led to the development of national space policy which seeks to limit the growth of the debris population and limit the risk to spacecraft and humans in space and on the Earth from debris. NASA has also been instrumental in developing consistent international policies and standards. Much of NASA's efforts have been to measure and characterize the orbital debris population. The U.S. Department of Defense tracks and catalogs spacecraft and large debris with it's Space Surveillance Network while NASA concentrates on research on smaller debris. In low Earth orbit, NASA has utilized short wavelength radars such as Haystack, HAX, and Goldstone to statistically characterize the population in number, size, altitude, and inclination. For higher orbits, optical telescopes have been used. Much effort has gone into the understanding and removal of observational biases from both types of measurements. NASA is also striving to understand the material composition and shape characteristics of debris to assess these effects on the risk to operational spacecraft. All of these measurements along with data from ground tests provide the basis for near- and long-term modeling of the environment. NASA also develops tools used by spacecraft builders and operators to evaluate spacecraft and mission designs to assess compliance with debris standards and policies which limit the growth of the debris environment.

Stansbery, Eugene G.

2009-01-01

328

Synchronization of unstable orbits using adaptive control  

NASA Astrophysics Data System (ADS)

We propose a method of controlling nonlinear and chaotic systems which is able to synchronize the phase space trajectory to a desired unstable orbit. The desired orbit could be an unstable periodic orbit or a chaotic orbit. The method uses the procedure of adaptive control and introduces time dependent changes in the system parameters. The changes in the parameter values depend on the deviations of the variables of the system from the desired orbit and the deviations of the controlled parameters from their values corresponding to the desired orbit. We illustrate our method using the Lorenz and Rössler systems. We also show that our method may be useful for communication purposes.

John, Jolly K.; Amritkar, R. E.

1994-06-01

329

d Orbitals in an Octahedral Ligand Field  

NSDL National Science Digital Library

Here is a page that shows the d orbitals in an axis set. Running the mouse over an orbital reveals the "name" of that orbital. This is good practice for helping students link the name of an orbital to the orientation. This page is linked to an interactive 3-dimensional applet, similar to the one above, that shows the d orbitals in an octahedral ligand field. The user may also click on the name of any one of the d orbitals to obtain a larger 3-dimensional image. The images are rotatable and scalable.

330

Orbital Pseudotumor: Distinct Diagnostic Features and Management  

PubMed Central

Purpose: To provide an overview of the spectrum of diseases known as ‘idiopathic orbital inflammatory syndrome’ also known as orbital pseudotumor, with emphasis on specific diagnostic challenges in the evaluation and management of patients with this disorder. Methods: Review of the relevant literature and summarize recent findings regarding the epidemiology, diagnosis, pathophysiology and treatment of orbital pseudotumor. Results: Orbital pseudotumor is a benign intraorbital process confined to the orbit but extra orbital involvement can occur. It is among the 3rd most common orbital diseases along with thyroid orbitopathy and lymphoproliferative disorder and accounts for 5-10% of orbital processes. Clinically, orbital pseudotumor has been categorized as myositis, dacryoadenitis, anterior, apical and diffuse process. Patients may present with diplopia, conjunctival chemosis, proptosis or abnormal computed tomography scan (CT-scan) findings. Patients may also have associated optic neuropathy. Diagnosis is based on careful history, ultrasonography (U/S), CT-scan and magnetic resonance imaging (MRI) studies which may also provide prognostic information. Treatment consists of systemic corticosteroids in the form of oral or intravenous administration. Confirmation is made by orbital biopsy. In addition to radiation, cytotoxic agents, immunosuppressant, IV immunoglobulin, biological therapy, TNF-alpha inhibitor monoclonal antibody and Mycophenolate Moftil have been found to be useful in the management of refractory orbital pseudotumor. Conclusion: Understanding of the clinical features of patients with orbital pseudotumor, differentiating it from other orbital processes by use of imaging techniques and timely implementation of available treatment strategies may help prevent visual loss and associated morbidity from this condition.

Chaudhry, Imtiaz A; Shamsi, Farrukh A; Arat, Yonca O; Riley, Fenwick C

2008-01-01

331

Orbits and Interiors of Planets  

NASA Astrophysics Data System (ADS)

The focus of this thesis is a collection of problems of timely interest in orbital dynamics and interior structure of planetary bodies. The first three chapters are dedicated to understanding the interior structure of close-in, gaseous extrasolar planets (hot Jupiters). In order to resolve a long-standing problem of anomalously large hot Jupiter radii, we proposed a novel magnetohydrodynamic mechanism responsible for inflation. The mechanism relies on the electro-magnetic interactions between fast atmospheric flows and the planetary magnetic field in a thermally ionized atmosphere, to induce electrical currents that flow throughout the planet. The resulting Ohmic dissipation acts to maintain the interior entropies, and by extension the radii of hot Jupiters at an enhanced level. Using self-consistent calculations of thermal evolution of hot Jupiters under Ohmic dissipation, we demonstrated a clear tendency towards inflated radii for effective temperatures that give rise to significant ionization of K and Na in the atmosphere, a trend fully consistent with the observational data. Furthermore, we found that in absence of massive cores, low-mass hot Jupiters can over-flow their Roche-lobes and evaporate on Gyr time-scales, possibly leaving behind small rocky cores. Chapters four through six focus on the improvement and implications of a model for orbital evolution of the solar system, driven by dynamical instability (termed the "Nice" model). Hydrodynamical studies of the orbital evolution of planets embedded in protoplanetary disks suggest that giant planets have a tendency to assemble into multi-resonant configurations. Following this argument, we used analytical methods as well as self-consistent numerical N-body simulations to identify fully-resonant primordial states of the outer solar system, whose dynamical evolutions give rise to orbital architectures that resemble the current solar system. We found a total of only eight such initial conditions, providing independent constraints for the solar system's birth environment. Next, we addressed a significant drawback of the original Nice model, namely its inability to create the physically unique, cold classical population of the Kuiper Belt. Specifically, we showed that a locally-formed cold belt can survive the transient instability, and its relatively calm dynamical structure can be reproduced. The last four chapters of this thesis address various aspects and consequences of dynamical relaxation of planetary orbits through dissipative effects as well as the formation of planets in binary stellar systems. Using octopole-order secular perturbation theory, we demonstrated that in multi-planet systems, tidal dissipation often drives orbits onto dynamical "fixed points," characterized by apsidal alignment and lack of periodic variations in eccentricities. We applied this formalism towards investigating the possibility that the large orbital eccentricity of the transiting Neptune-mass planet Gliese 436b is maintained in the face of tidal dissipation by a second planet in the system and computed a locus of possible orbits for the putative perturber. Following up along similar lines, we used various permutations of secular theory to show that when applied specifically to close-in low-mass planetary systems, various terms in the perturbation equations become separable, and the true masses of the planets can be solved for algebraically. In practice, this means that precise knowledge of the system's orbital state can resolve the sin( i) degeneracy inherent to non-transiting planets. Subsequently, we investigated the onset of chaotic motion in dissipative planetary systems. We worked in the context of classical secular perturbation theory, and showed that planetary systems approach chaos via the so-called period-doubling route. Furthermore, we demonstrated that chaotic strange attractors can exist in mildly damped systems, such as photo-evaporating nebulae that host multiple planets. Finally, we considered planetary formation in highly inclined binary systems,

Batygin, Konstantin

2012-05-01

332

Management of ocular, orbital, and adnexal trauma  

SciTech Connect

This book contains 20 chapters. Some of the chapter titles are: The Ruptured Globe: Primary Care; Corneal Trauma, Endophthalmitis; Antibiotic Usage; Radiology of Orbital Trauma; Maxillofacial Fractures; Orbital Infections; and Basic Management of Soft Tissue Injury.

Spoor, T.C.; Nesi, F.A.

1988-01-01

333

Dedifferentiated chondrosarcoma arising in the orbit.  

PubMed Central

Orbital chondrosarcomas are extremely rare and are usually an extension of tumours involving the paranasal sinuses. A unique case of dedifferentiated chondrosarcoma arising solely within the orbit is presented. Images

Potts, M J; Rose, G E; Milroy, C; Wright, J E

1992-01-01

334

Spin-Orbital Texture in Topological Insulators  

NASA Astrophysics Data System (ADS)

For three-dimensional topological insulators in the Bi2Se3 family, topological surface states with pz orbitals have a left-handed spin texture for the upper Dirac cone and a right-handed spin texture for the lower Dirac cone. In this work, we predict a new form of the spin-orbital texture associated with the px and py orbitals. For the upper Dirac cone, a left-handed (right-handed) spin texture is coupled to the “radial” (“tangential”) orbital texture, whereas for the lower Dirac cone, the coupling of spin and orbital textures is the exact opposite. The “tangential” (“radial”) orbital texture is dominant for the upper (lower) Dirac cone, leading to the right-handed spin texture for the in-plane orbitals of both the upper and lower Dirac cones. A spin-resolved and photon polarized angle-resolved photoemission spectroscopy experiment is proposed to observe this novel spin-orbital texture.

Zhang, Haijun; Liu, Chao-Xing; Zhang, Shou-Cheng

2013-08-01

335

Autonomous Space Processor for Orbital Debris.  

National Technical Information Service (NTIS)

Advanced designs are being continued to develop the ultimate goal of a GETAWAY special to demonstrate economical removal of orbital debris utilizing local resources in orbit. The fundamental technical feasibility was demonstrated in 1988 through theoretic...

K. Ramohalli D. Campbell M. Marine M. Saad D. Bertles

1990-01-01

336

Autonomous Space Processor for Orbital Debris.  

National Technical Information Service (NTIS)

This work continues to develop advanced designs toward the ultimate goal of a Get Away Special to demonstrate economical removal of orbital debris using local resources in orbit. The fundamental technical feasibility was demonstrated in 1988 through theor...

1990-01-01

337

Orbiter CIU/IUS communications hardware evaluation  

NASA Technical Reports Server (NTRS)

Inertial Upper Stage (IUS) and DoD Communication Interface Unit (CIU) communication system design, hardware specifications, and interfaces were evaluated to determine their compatibility with the Orbiter payload communication and data handling equipment and the Orbiter network communication equipment.

Huth, G. K.

1979-01-01

338

Eye Socket Fracture (Fracture of the Orbit)  

MedlinePLUS

... impact to the face, most commonly by an automobile dashboard or steering wheel during a car crash. ... such as a baseball, a fist or an automobile dashboard. Direct orbital floor fracture. If an orbital ...

339

Orbiter Kapton wire operational requirements and experience  

NASA Technical Reports Server (NTRS)

The agenda of this presentation includes the Orbiter wire selection requirements, the Orbiter wire usage, fabrication and test requirements, typical wiring installations, Kapton wire experience, NASA Kapton wire testing, summary, and backup data.

Peterson, R. V.

1994-01-01

340

ERS-1: 18 Months in Orbit.  

National Technical Information Service (NTIS)

Viewgraphs of the ERS-1 mission outline initial objectives, the orbit configuration, the instrumentation, the international cooperation, and the objectives still to be achieved. Graphs of specified performances include orbit control, inclination correctio...

J. Louet

1993-01-01

341

Rational orbits around charged black holes  

SciTech Connect

We show that all eccentric timelike orbits in Reissner-Nordstroem spacetime can be classified using a taxonomy that draws upon an isomorphism between periodic orbits and the set of rational numbers. By virtue of the fact that the rationals are dense, the taxonomy can be used to approximate aperiodic orbits with periodic orbits. This may help reduce computational overhead for calculations in gravitational wave astronomy. Our dynamical systems approach enables us to study orbits for both charged and uncharged particles in spite of the fact that charged particle orbits around a charged black hole do not admit a simple one-dimensional effective potential description. Finally, we show that comparing periodic orbits in the Reissner-Nordstroem and Schwarzschild geometries enables us to distinguish charged and uncharged spacetimes by looking only at the orbital dynamics.

Misra, Vedant [Physics Department, Columbia University, New York, New York 10027 (United States); Levin, Janna [Department of Physics and Astronomy, Barnard College of Columbia University, 3009 Broadway, New York, New York 10027 (United States); Institute for Strings, Cosmology and Astroparticle Physics, Columbia University, New York, New York 10027 (United States)

2010-10-15

342

Two designs for an orbital transfer vehicle  

NASA Technical Reports Server (NTRS)

The Orbital Transfer Vehicle (OTV) and systems were researched in the following areas: avionics, crew systems, electrical power systems, environmental control/life support systems, navigation and orbital maneuvers, propulsion systems, reaction control systems (RCS), servicing systems, and structures.

Davis, Richard; Duquette, Miles; Fredrick, Rebecca; Schumacher, Daniel; Somers, Schaeffer; Stafira, Stanley; Williams, James; Zelinka, Mark

1988-01-01

343

MOOSE: Manned On-Orbit Servicing Equipment  

NASA Technical Reports Server (NTRS)

The ability to service satellites has thus far been limited to low earth orbit platforms within reach of the Space Shuttle. Other orbits, such as geosynchronous orbits containing high-value spacecraft have not been attainable by a servicing vehicle. The useful life of a satellite can be extended by replacing spent propellant and damaged orbital replacement units, forestalling the need for eventual replacement. This growing need for satellite on-orbits servicing can be met by the Manned On-Orbit Servicing Equipment (MOOSE). Missions requiring orbit transfer capability, precision manipulation and maneuvering, and man-in-the-loop control can be accomplished using MOOSE. MOOSE is a flexible, reusable, single operator, aerobraking spacecraft designed to refuel, repair, and service orbiting spacecraft. MOOSE will be deployed from Space Station Freedom, (SSF), where it will be stored, resupplied, and refurbished.

Budinoff, J. (editor); Leontsinis, N. (editor); Lane, J. (editor); Singh, R. (editor); Angelone, K.; Boswell, C.; Chamberlain, I.; Concha, M.; Corrodo, M.; Custodio, O.

1993-01-01

344

Orbits in Adiabatically Contracting Spherical Potentials  

NASA Astrophysics Data System (ADS)

It was recently shown in N-body simulations that the simple adiabatic invariant r M(r) describes the evolution of a contracting spherical density distribution very well. This is surprising as this adiabatic invariant is only valid for circular orbits. Orbits in spherically symmetric potentials resemble rather precessing ellipses. We want to highlight some problems involved in proving the validity of the adiabatic approximation on a orbit to orbit basis. Statistical methods are more promising.

Jesseit, R.; Burkert, A.

345

The origin of Pluto's peculiar orbit  

Microsoft Academic Search

THE origin of Pluto's unusual orbit---the most eccentric and inclined of all the planets---remains a mystery. The orbits of Pluto and Neptune overlap, but close approaches of these two planets are prevented by the existence of a resonance condition1: Pluto's orbital period is exactly 3\\/2 that of Neptune, which ensures that the conjunctions always occur near Pluto's aphelion. Long-term orbit

Renu Malhotra

1993-01-01

346

Orbital Structure of Triaxial Black Hole Nuclei  

Microsoft Academic Search

Orbital motion in triaxial nuclei with central point masses, representing supermassive black holes, is investigated. The stellar density is assumed to follow a power law rho~r-gamma, with gamma=1 or gamma=2. At low energies the motion is essentially regular; the major families of orbits are tubes and pyramids. Pyramid orbits are similar to box orbits but have their major elongation parallel

M. Y. Poon; D. Merritt

2001-01-01

347

Low thrust orbit determination program  

NASA Technical Reports Server (NTRS)

Logical flow and guidelines are provided for the construction of a low thrust orbit determination computer program. The program, tentatively called FRACAS (filter response analysis for continuously accelerating spacecraft), is capable of generating a reference low thrust trajectory, performing a linear covariance analysis of guidance and navigation processes, and analyzing trajectory nonlinearities in Monte Carlo fashion. The choice of trajectory, guidance and navigation models has been made after extensive literature surveys and investigation of previous software. A key part of program design relied upon experience gained in developing and using Martin Marietta Aerospace programs: TOPSEP (Targeting/Optimization for Solar Electric Propulsion), GODSEP (Guidance and Orbit Determination for SEP) and SIMSEP (Simulation of SEP).

Hong, P. E.; Shults, G. L.; Huling, K. R.; Ratliff, C. W.

1972-01-01

348

[Orbital decompression in Grave's ophtalmopathy].  

PubMed

Graves disease orbitopathy is a complex progressive inflammatory disease. Medical treatment remains in all cases the proposed treatment of choice. Surgical treatment by bone decompression can be considered as an emergency mainly in cases of optic neuropathy or ocular hypertension not being controlled medically or in post-traumatic exophthalmos stage. Emergency bone decompression eliminates compression or stretching of the optic nerve allowing visual recovery. The uncontrolled ocular hypertension will benefit from decompression. The normalization of intraocular pressure may be obtained by this surgery or if needed by the use of postoperative antiglaucoma drops or even filtration surgery. In all operated cases, the IOP was normalized with an average decrease of 7.71 mmHg and a cessation of eye drops in 3/7 cases. Regarding sequelae, our therapeutic strategy involves consecutively surgery of the orbit, extraocular muscles and eyelids. The orbital expansion gives excellent results on the cosmetic level and facilitates the implementation of subsequent actions. PMID:21284231

Longueville, E

2010-01-01

349

Analytic theory of orbit contraction  

NASA Technical Reports Server (NTRS)

The motion of a satellite in orbit, subject to atmospheric force and the motion of a reentry vehicle are governed by gravitational and aerodynamic forces. This suggests the derivation of a uniform set of equations applicable to both cases. For the case of satellite motion, by a proper transformation and by the method of averaging, a technique appropriate for long duration flight, the classical nonlinear differential equation describing the contraction of the major axis is derived. A rigorous analytic solution is used to integrate this equation with a high degree of accuracy, using Poincare's method of small parameters and Lagrange's expansion to explicitly express the major axis as a function of the eccentricity. The solution is uniformly valid for moderate and small eccentricities. For highly eccentric orbits, the asymptotic equation is derived directly from the general equation. Numerical solutions were generated to display the accuracy of the analytic theory.

Vinh, N. X.; Longuski, J. M.; Busemann, A.; Culp, R. D.

1977-01-01

350

On-orbit spacecraft reliability  

NASA Technical Reports Server (NTRS)

Operational and historic data for 350 spacecraft from 52 U.S. space programs were analyzed for on-orbit reliability. Failure rates estimates are made for on-orbit operation of spacecraft subsystems, components, and piece parts, as well as estimates of failure probability for the same elements during launch. Confidence intervals for both parameters are also given. The results indicate that: (1) the success of spacecraft operation is only slightly affected by most reported incidents of anomalous behavior; (2) the occurrence of the majority of anomalous incidents could have been prevented piror to launch; (3) no detrimental effect of spacecraft dormancy is evident; (4) cycled components in general are not demonstrably less reliable than uncycled components; and (5) application of product assurance elements is conductive to spacecraft success.

Bloomquist, C.; Demars, D.; Graham, W.; Henmi, P.

1978-01-01

351

Orbit monitoring in the SLC  

SciTech Connect

Beam orbits in the SLC are monitored in real time and the data is stored for future trend and correlation analysis. A background process acquires Beam Position Monitor (BPM) and Toroid data on a periodic basis and saves the general quantities such as orbit RMS and beam intensity in addition to the individual readings. Some of this data is archived by the SLC History Buffer facility and the rest is saved in files for later analysis. This has permitted the tracing of interaction point instabilities to specific devices as far away as the damping rings. In addition, the data is displayed for the operators both in summary and in full form. The different displays can be configured from the control consoles. 2 refs., 5 figs.

Sanchez-Chopitea, L.; Emma, P.; Van Olst, D.

1991-05-01

352

Viking Orbiter: Views of Mars  

NSDL National Science Digital Library

This website is an electronic version of an historical NASA (National Aeronautics and Space Administration) publication containing information about the Viking Orbiter and images it took of the planet Mars. This book incorporates images acquired by the Viking orbiters beginning in 1976. The pictures here represent only a small fraction of the many thousands taken, and were chosen to illustrate the diverse geology and atmospheric phenomena of Mars. General information about the Viking mission highlights the purpose of sending these two spacecraft to the planet Mars. The images contain descriptions and explanations of what is being shown and cover planetary features such as channels, Valles Marineris canyon, volcanic features and Olympus Mons, comparison between Earth and Mars, deformation, craters, the moons Phobos and Deimos, surface processes (wind, mass wasting), polar regions, planet color, atmosphere and the Viking 1 and Viking 2 landing sites.

1980-05-09

353

The Orbiting Primate Experiment (OPE)  

NASA Technical Reports Server (NTRS)

Instrumentation and life support systems are described for an experiment to determine the physiological effects of long term space flight on unrestrained, minimally instrumented rhesus macaques flown in orbit for periods up to six months or one year. On return from orbit, vestibular, cardiovascular, and skeletal muscle function will be tested. Blood chemistry and hematological studies will be conducted as well as tests of the immunological competence of selected animals. Nasal, rectal, and throat swabs will be used for bacterial and viral studies, and histopathological and histochemical investigations will be be made of all organs using light and electron microscopy. The experiment is being considered as a payload for the biomedical experiment scientific satellite.

Bourne, G. H.; Debourne, M. N. G.; Mcclure, H. M.

1977-01-01

354

Synchronous orbit power technology needs  

NASA Technical Reports Server (NTRS)

An attempt is made to define the needs for future geosynchronous spacecraft power subsystem components, including power generation, energy storage, and power processing. Three projected models (a mission model, an orbit transfer vehicle model, and a mass model) for power subsystem components are used to define power requirements and mass limitations for future spacecraft. Based upon these models, the power subsystems for a 10-kW, 10-year-life, dedicated spacecraft and for a 20-kW, 20-year-life multimission platform are analyzed to establish power density requirements for orbit transfer vehicles. Comparison of these requirements to state-of-the-art (Intelsat 5) design values shows that major improvements, by a factor of 2 or more, are needed to accomplish the near term missions.

Slifer, L. W., Jr.; Billerbeck, W. J.

1979-01-01

355

Has Nemesis' orbit been detected?  

NASA Technical Reports Server (NTRS)

The orbital angular momenta of 126 very young comets are calculated from the orbital data of Marsden and Roemer (1982) and analyzed statistically. A large anisotropy is detected in a plane almost perpendicular to the ecliptic and shown to have a characteristic dissipation lifetime of 10-30 Myr. Dynamic evolution computations indicate that the impulse which produced the anisotropy is that of a very slow massive (10-90 Jupiter mass) body, which is bound to the solar system, passed its 15,000-35,000-AU perihelion about 2-15 Myr ago, and has period 5-50 Myr. It is suggested that this body could well be identical to Nemesis, the object proposed to explain mass faunal extinctions.

Delsemme, A. H.

1986-01-01

356

The Mercury Dual Orbiter mission  

NASA Technical Reports Server (NTRS)

The Mercury Orbiter (MeO) will carry out a full range of particles, fields, and planetary imaging science at Mercury. Present mission plans call for a launch in 1999 with a flight time of about 4.5 years. By means of multiple Venus and Mercury gravitational assists, the mission can be accomplished with present U.S. launch vehicles and a very large payload can be placed in orbit around Mercury. The dual-spacecraft concept will permit outstanding scientific study of solar cosmic rays and the solar wind throughout the inner heliosphere from 0.3 AU to 1.0 AU. Modest enhancements to the planned magnetospheric instruments and utilization of onboard solar instruments will permit unique investigation of solar particle acceleration and transport with the MeO spacecraft.

Baker, D. N.; Slavin, J. A.

1990-01-01

357

Orbital changes during hypersonic aerocruise  

NASA Technical Reports Server (NTRS)

A novel mathematical approach that allows the analysis of orbital changes occurring during an aerocruise maneuver to be conducted in two distinct stages is presented. In the first stage, the aerodynamic turn is determined using a nondimensional form of the equations of motion that is free of singularities, and the way in which speed, altitude, angle of attack, and thrust direction should be chosen to maximize the aerodynamic turn for a given propellant expenditure is demonstrated. In the second analysis stage, the aerodynamic turn is translated into changes in the orbital elements with respect to the equatorial plane; analytic solutions for the initial arguments of latitude that maximize the change in inclination and in the longitude of the ascending node are given. As the initial inclination decreases toward zero, the optimal location moves from the apex toward the node.

Mease, Kenneth D.; Vinh, Nguyen X.; Lee, Jaemyong

1987-01-01

358

The Mercury dual orbiter mission  

NASA Astrophysics Data System (ADS)

The Mercury Orbiter (MeO) will carry out a full range of particles, fields, and planetary imaging science at Mercury. Present mission plans call for a launch in 1999 with a flight time of about 4.5 years. By means of multiple Venus and Mercury gravitational assists, the mission can be accomplished with present U.S. launch vehicles and a very large payload can be placed in orbit around Mercury. The dual-spacecraft concept will permit outstanding scientific study of solar cosmic rays and the solar wind throughout the inner heliosphere from 0.3 AU to 1.0 AU. Modest enhancements to the planned magnetospheric instruments and utilization of onboard solar instruments will permit unique investigation of solar particle acceleration and transport with the MeO spacecraft.

Baker, D. N.; Slavin, J. A.

1990-03-01

359

Viking orbiter system primary mission  

NASA Technical Reports Server (NTRS)

An overview of Viking Orbiter (VO) system and subsystem performances during the primary mission (the time period from VO-1 launch on August 20, 1975, through November 15, 1976) is presented. Brief descriptions, key design requirements, pertinent historical information, unique applications or situations, and predicted versus actual performances are included for all VO-1 and VO-2 subsystems, both individually and as an integrated system.

Goudy, J. R.

1977-01-01

360

In-orbit Microaccelerometric Experiment  

NASA Astrophysics Data System (ADS)

In-orbit tests were conducted on a recently constructed high-sensitivity microaccelerometer consisting of a cubic proof-mass suspended in cubic cavity. The instruments (which is part of the project called MACEK) was first tested in a laboratory and then on a Russian-made Resource-F-1 type satellite flying in a very low-earth trajectory. The paper presents accelerometric measurements and the interpretation of results.

Peresty, R.; Sehnal, L.

1992-08-01

361

Orbital assembly and maintenance study  

NASA Technical Reports Server (NTRS)

The requirements, conceptual design, tradeoffs, procedures, and techniques for orbital assembly of the support structure of the microwave power transmission system and the radio astronomy telescope are described. Thermal and stress analyses, packaging, alignment, and subsystems requirements are included along with manned vs. automated and transportation tradeoffs. Technical and operational concepts for the manned and automated maintenance of satellites were investigated and further developed results are presented.

Gorman, D.; Grant, C.; Kyrias, G.; Lord, C.; Rombach, J.; Salis, M.; Skidmore, R.; Thomas, R.

1975-01-01

362

Vigilance problems in orbiter processing  

NASA Technical Reports Server (NTRS)

A pilot experiment was done to determine what factors influence potential performance errors related to vigilance in Orbiter processing activities. The selected activities include post flight inspection for burned gap filler material and pre-rollout inspection for tile processing shim material. It was determined that the primary factors related to performance decrement were the color of the target and the difficulty of the target presentation.

Swart, William W.; Safford, Robert R.; Kennedy, David B.; Yadi, Bert A.; Barth, Timothy S.

1993-01-01

363

Opportunity Tracks Seen from Orbit  

NASA Technical Reports Server (NTRS)

[figure removed for brevity, see original site] Figure 1

NASA's Mars Exploration Rover Opportunity landed on the red planet a year ago. This enhanced-resolution image from the Mars Orbiter Camera on NASA's Mars Global Surveyor orbiter is the only picture obtained thus far (by Jan. 24, 2005) that shows the tracks made by Opportunity.

The image was acquired on April 26, 2004, during Opportunity's 91st martian day, or sol. That was the first day of Opportunity's extended mission, and the rover had recently completed exploration of small 'Fram Crater' on the route from its landing site toward 'Endurance Crater,' where it would eventually spend six months. The rover itself can be seen in this image -- an amazing accomplishment, considering that the orbiter was nearly 400 kilometers (nearly 250 miles) away at the time! Also visible and labeled on this image are the spacecraft's lander, backshell, parachute and heat shield, plus effects of its landing rockets.

The camera captured this image with use of a technique called compensated pitch and roll targeted observation. In this method, the entire spacecraft rolls as it passes over the target area so the camera can scan in a way that sees details at three times higher resolution than the camera's normal high-resolution capability.

The tracks made by Opportunity on the sandy surface of Meridiani Planum are not quite as visible from orbit as are the tracks made in Gusev Crater by the other Mars Exploration Rover, Spirit. A dustier surface at the Spirit site increases contrast between the tracks and the surrounding surfaces. Indeed, some parts of the track made by Opportunity are not visible in this image. Sunlight illuminates the scene from the left. North is toward the top of the image. The 100-meter scale bar is 109 yards long.

2005-01-01

364

Cassini-Huygens in Orbit Around Saturn  

NASA Technical Reports Server (NTRS)

The Cassini-Huygens spacecraft was successfully placed in an orbit about Saturn on June 30, 2004. Starting with our approach to Saturn, the instruments carried by the Orbiter have been very active since early 2004. The Huygens probe mission was also recently completed. As a result, all of the Cassini Orbiter investigations and Huygens Probe investigations have scientific results to report.

Matson, Dennis L.; Lebreton, Jean-Pierre; Spilker, J.

2005-01-01

365

Analytic central orbits and their transformation group  

NASA Astrophysics Data System (ADS)

A useful crude approximation for Abelian functions is developed and applied to orbits. The bound orbits in the power-law potentials A r-? take the simple form (l/r)k = 1 + e cos (m ?), where k = 2 - ? > 0 and l and e are generalizations of the semi-latus-rectum and the eccentricity. m is given as a function of `eccentricity'. For nearly circular orbits m is , while the above orbit becomes exact at the energy of escape where e is 1 and m is k. Orbits in the logarithmic potential that gives rise to a constant circular velocity are derived via the limit ? -> 0. For such orbits, r2 vibrates almost harmonically whatever the `eccentricity'. Unbound orbits in power-law potentials are given in an appendix. The transformation of orbits in one potential to give orbits in a different potential is used to determine orbits in potentials that are positive powers of r. These transformations are extended to form a group which associates orbits in sets of six potentials, e.g. there are corresponding orbits in the potentials proportional to r, r-2/3, r-3, r-6, r-4/3 and r4. A degeneracy reduces this to three, which are r-1, r2 and r-4 for the Keplerian case. A generalization of this group includes the isochrone with the Kepler set.

Lynden-Bell, D.; Jin, S.

2008-05-01

366

Conversion Between Osculating and Mean Orbital Elements  

NASA Technical Reports Server (NTRS)

Osculating/Mean Orbital Element Conversion (C version) (OSMEANC) is a C-language computer program that performs precise conversions between osculating and mean classical orbital elements. OSMEANC can be used for precise design of spacecraft missions and maneuvers and precise calculation of planetary orbits. The program accounts for the full complexity of gravitational fields, including aspherical and third-body effects.

Guinn, Joseph; Chung, Min-Kun; Vincent, Mark

2006-01-01

367

MOOSE: Manned on-Orbit Servicing Equipment.  

National Technical Information Service (NTIS)

The ability to service satellites has thus far been limited to low earth orbit platforms within reach of the Space Shuttle. Other orbits, such as geosynchronous orbits containing high-value spacecraft have not been attainable by a servicing vehicle. The u...

J. Budinoff N. Leontsinis J. Lane R. Singh K. Angelone

1993-01-01

368

Navigation of Spacecraft in Unstable Orbital Environments  

Microsoft Academic Search

The novelty of libration point orbits is their hyperbolic instability. It is this basic property that allows them to serve as connections between disparate regions of space, and gives them their many practical uses. This same property also makes the navigation of spacecraft in libration point orbits a fascinating subject, one which exposes new questions in orbit determination and control.

D. J. Scheeres

369

TDRS orbit determination by radio interferometry  

Microsoft Academic Search

In support of a NASA study on the application of radio interferometry to satellite orbit determination, MITRE developed a simulation tool for assessing interferometry tracking accuracy. The Orbit Determination Accuracy Estimator (ODAE) models the general batch maximum likelihood orbit determination algorithms of the Goddard Trajectory Determination System (GTDS) with the group and phase delay measurements from radio interferometry. ODAE models

Michael S. Pavloff

1994-01-01

370

Mars Reconnaissance Orbiter Operational Aerobraking Phase Assessment.  

National Technical Information Service (NTIS)

The Mars Reconnaissance Orbiter (MRO) was inserted into orbit around Mars on March 10, 2005. After a brief delay, it began the process of aerobraking - using the atmospheric drag on the vehicle to reduce orbital period. The aerobraking phase lasted approx...

J. L. Prince S. A. Striepe

2007-01-01

371

Orbital motion of the solar power satellite  

Microsoft Academic Search

A study on the effects of solar radiation pressure on the SPS orbit is documented. It was shown that the eccentricity of the orbit can increase from initially being zero. The SPS configuration is primarily considered but the results are applicable to any geosynchronous satellite that resembles a flat surface continually facing the sun. The orbital evolution of the SPS

O. F. Graf Jr.; O. F. Jr

1977-01-01

372

Bone erosion caused by orbital cavernous hemangioma  

Microsoft Academic Search

Bone erosion is commonly associated with malignant or infiltrative orbital lesions. It is unusual to have bone erosion in\\u000a association with benign focal orbital tumors. We report a case of large orbital cavernous hemangioma that showed bone erosion\\u000a on computed tomography.

Riad N. Ma'luf; Nabil J. Khoury; Usama M. Hadi

2000-01-01

373

The Meaning of d-Orbital Labels  

ERIC Educational Resources Information Center

The orbital labels when considered as the angular part of the wavefunction can serve as an inclusive principle, which the students can use to construct the spatial shapes of the d orbitals from their labels. The spatial orientation of the different d orbitals guides the crystal field theory which includes d(sub xy), d(sub yz) and d(sub xz) lying…

Ashkenazi, Guy

2005-01-01

374

The geostationary orbit and developing countries  

NASA Technical Reports Server (NTRS)

The geostationary orbit is becoming congested due to use by several countries throughout the world, and the request for use of this orbit is increasing. There are 188 geostationary stations in operation. An equitable distribution of stations on this orbit is requested.

Medina, E. R.

1982-01-01

375

Some Observations on Molecular Orbital Theory  

ERIC Educational Resources Information Center

A few flawed predictions in the context of homonuclear diatomic molecules are presented in order to introduce students to molecular orbital (MO) theory. A common misrepresentation of the relationship between the energy of an atomic orbital and the energy of the MO associated with the atomic orbital is illustrated.

Journal of Chemical Education, 2005

2005-01-01

376

CELEST Computer Program for Computing Satellite Orbits.  

National Technical Information Service (NTIS)

The Celest Computer Program uses raw Doppler data to determine satellite orbits. It provides diagnostic information on the quality of the orbits and the data used in producing those orbits. The basic technique employed is one of weighted least squares whe...

J. W. O'Toole

1976-01-01

377

CELEST computer program for computing satellite orbits  

Microsoft Academic Search

The CELEST Computer Program uses raw Doppler data to determine satellite orbits. It provides diagnostic information on the quality of the orbits and the data used in producing those orbits. The basic technique employed is one of weighted least squares where the data is edited and weighted within the program. An iterative capability exists for nonlinear problems. Trajectories are formed

J. W. Otoole

1976-01-01

378

Some amazing properties of spherical nilpotent orbits  

Microsoft Academic Search

Let $\\\\g$ be simple Lie algebra. We give a conceptual proof for the fact that the nilpotent orbits of height 3 are spherical. It is shown that if the highest root of $\\\\g$ is fundamental, then $\\\\g$ has a specific nilpotent orbit of height 3. This orbit satisfies several interesting relations. Moreover, it can be used for an intrinsic construction

Dmitri I. Panyushev

2002-01-01

379

Synchronous orbit power technology needs  

NASA Technical Reports Server (NTRS)

The needs are defined for future geosynchronous orbit spacecraft power subsystem components, including power generation, energy storage, and power processing. A review of the rapid expansion of the satellite communications field provides a basis for projection into the future. Three projected models, a mission model, an orbit transfer vehicle model, and a mass model for power subsystem components are used to define power requirements and mass limitations for future spacecraft. Based upon these three models, the power subsystems for a 10 kw, 10 year life, dedicated spacecraft and for a 20 kw, 20 year life, multi-mission platform are analyzed in further detail to establish power density requirements for the generation, storage and processing components of power subsystems as related to orbit transfer vehicle capabilities. Comparison of these requirements to state of the art design values shows that major improvements, by a factor of 2 or more, are needed to accomplish the near term missions. However, with the advent of large transfer vehicles, these requirements are significantly reduced, leaving the long lifetime requirement, associated with reliability and/or refurbishment, as the primary development need. A few technology advances, currently under development, are noted with regard to their impacts on future capability.

Slifer, L. W., Jr.; Billerbeck, W. J.

1979-01-01

380

On charge and orbital ordering  

NASA Astrophysics Data System (ADS)

In recent times there has been a resurgence of interest in the properties of transition metal oxides because of the wide range of physical properties that they exhibit. Recent developments in experimental techniques offer a direct probe to the novel types of ordering realised in these systems. Using first principle band structure calculations, we have critically examined^1 the results of resonant x-ray scattering experiments which are believed to directly probe charge and orbital ordering. Considering the specific case of La_0.5Sr_1.5MnO_4, we show that this technique actually probes most directly and sensitively small structural distortions in the system. Such distortions, often difficult to detect with more conventional techniques, invariably accompany and usually cause the orbital and charge orderings. In this sense, this technique is only an indirect probe of such types of ordering. Our results also provide a microscopic explanation of the novel types of charge and orbital ordering realized in this system and other doped manganites. 1. Priya Mahadevan, K. Terakura and D.D. Sarma, Phys. Rev. Lett. 87, 066404 (2001).

Mahadevan, Priya; Terakura, K.; Sarma, Dd

2002-03-01

381

Full Orbit PIC in NIMROD  

NASA Astrophysics Data System (ADS)

The primary goal of the Plasma Science and Innovation Center (PSI Center) is to refine and optimize existing MHD codes to achieve improved predictability for emerging concept (EC) experiments. Kinetic effects have been shown to play a dominant role in some EC experiments, particularly in FRC stability[1]. The PSI Center has extended the hybrid kinetic-MHD implementation in NIMROD[2] from the drift kinetic model to the full kinetic model to include sufficient physics to accurately account for these effects, in particular large Larmour radius. The Boris push has been implemented for particles in NIMROD. However, this places a severe time step restriction on the particle time step. Time step restrictions have been decreased by using orbit averaging. Orbit averaging has been implemented for both full and drift kinetic equations and shows no significant impact on linear growth rates for tested regimes. We will show preliminary results from the implementation of full orbit (Lorentz force) particles coupled to the NIMROD code. [1] E. Belova et.al. ``Numerical Study of tilt stability of prolate field-reversed configurations,'' PoP, 7, 4996, 2000 [2] C.C. Kim et.al. ``Hybrid Kinetic-MHD Simulations in General Geometry,'' CPC, 164, 448, 2004.

Kim, Charlson

2006-10-01

382

Idiopathic Orbital Inflammation Syndrome with Retro-Orbital Involvement: A Retrospective Study of Eight Patients  

PubMed Central

Background The aim of this retrospective study was to document the clinical findings and radiological features of idiopathic orbital inflammation syndrome with retro-orbital involvement. Methods We searched for ophthalmological patients who received orbital imaging at Zhejiang Provincial People's Hospital between October 2003 and April 2010. Seventy-three patients were diagnosed with idiopathic orbital inflammation syndrome based on clinicoradiological features, with pathological confirmation of nonspecific inflammatory conditions in 47 patients. Eight patients (11%) had MRI or CT evidence of retro-orbital involvement. All 8 patients were diagnosed with idiopathic orbital inflammation syndrome after biopsy of the orbital lesion. MR images were obtained for all 8 patients; 3 patients also had a contrast-enhanced CT scan. Results Seven out of 8 patients with retro-orbital involvement also had orbital apex lesions. Of the 65 patients without retro-orbital involvement, 19 had orbital apex lesions. The difference in the number of patients with orbital apex lesions between the two populations was significant (Fisher exact test P?=?.002). In all 8 patients with retro-orbital involvement, the inflammation spread through the superior orbital fissure. The retro-orbital lesions were isointense to grey matter on T1-weighted images, hypointense on T2-weighted images, and displayed uniform contrast enhancement; on contrast-enhanced CT scans, they were hyperdense relative to the contralateral mirror area and had radiological contours that were similar to those seen on MR images. The diffuse inflammation with marked sclerosis and hyalinization that we observed in the patients with retro-orbital involvement is consistent with the diagnosis of the sclerosing subtype of idiopathic orbital inflammation syndrome. All 8 patients also complained of mild to moderate periorbital pain (headache). Conclusions In patients with idiopathic orbital inflammation syndrome, it is important to perform MRI and CT scans to identify possible retro-orbital involvement. Retro-orbital involvement is more frequent when the lesion is present in the orbital apex.

Li, Yumei; Lip, Gerald; Chong, Vincent; Yuan, Jianhua; Ding, Zhongxiang

2013-01-01

383

Artificial Martian frozen orbits and Sun-Synchronous orbits using continuous low-thrust control  

NASA Astrophysics Data System (ADS)

This paper analyses three types of artificial orbits around Mars pushed by continuous low-thrust control: artificial frozen orbits, artificial Sun-Synchronous orbits and artificial Sun-Synchronous frozen orbits. These artificial orbits have similar characteristics to natural frozen orbits and Sun-Synchronous orbits, and their orbital parameters can be selected arbitrarily by using continuous low-thrust control. One control strategy to achieve the artificial frozen orbit is using both the transverse and radial continuous low-thrust control, and another to achieve the artificial Sun-Synchronous orbit is using the normal continuous low-thrust control. These continuous low-thrust control strategies consider J 2, J 3, and J 4 perturbations of Mars. It is proved that both control strategies can minimize characteristic velocity. Relevant formulas are derived, and numerical results are presented. Given the same initial orbital parameters, the control acceleration and characteristic velocity taking into account J 2, J 3, and J 4 perturbations are similar to those taking into account J 2 perturbations for both Mars and the Earth. The control thrust of the orbit around Mars is smaller than that around the Earth. The magnitude of the control acceleration of ASFOM-4 (named as Artificial Sun-Synchronous Frozen Orbit Method 4) is the lowest among these strategies and the characteristic velocity within one orbital period is only 0.5219 m/s for the artificial Sun-Synchronous frozen orbit around Mars. It is evident that the relationship among the control thrusts and the primary orbital parameters of Martian artificial orbits is always similar to that of the Earth. Simulation shows that the control scheme extends the orbital parameters' selection range of three types of orbits around Mars, compared with the natural frozen orbit and Sun-Synchronous orbit.

Wu, Zhigang; Jiang, Fanghua; Li, Junfeng

2014-05-01

384

Orbital hardness tensors from hydrogen through xenon from Kohn-Sham perturbed orbitals  

Microsoft Academic Search

A systematic study of the orbital hardness tensor and total hardness for atoms ranging from H to Xe is presented. Results are obtained by the use of an efficient algorithm for the computation of density functional-based orbital reactivity indices exploring the concept of fractional occupations. So, the orbital reactivity indices are defined within the space spanned by the orbital occupation

Tzonka Mineva; Thomas Heine

2006-01-01

385

Cranio-orbital Minicraniotomy for Orbital Lesions: Surgical Experience of 28 Patients  

Microsoft Academic Search

Objective: The cranio-orbital minicraniotomy is a modification of the subfrontal approach with orbital osteotomy. The purpose of this study is to describe the technique of this approach and evaluate the outcome in 28 consecutive patients suffering from various orbital lesions. Methods: This is a retrospective study carried out on 28 patients having different orbital lesions. All the patients were operated

Ali Kotb Ali

2008-01-01

386

The orbital record in stratigraphy  

NASA Technical Reports Server (NTRS)

Orbital signals are being discovered in pre-Pleistocene sediments. Due to their hierarchical nature these cycle patterns are complex, and the imprecision of geochronology generally makes the assignment of stratigraphic cycles to specific orbital cycles uncertain, but in sequences such as the limnic Newark Group under study by Olsen and pelagic Cretaceous sequence worked on by our Italo-American group the relative frequencies yield a definitive match to the Milankovitch hierarchy. Due to the multiple ways in which climate impinges on depositional systems, the orbital signals are recorded in a multiplicity of parameters, and affect different sedimentary facies in different ways. In platform carbonates, for example, the chief effect is via sea-level variations (possibly tied to fluctuating ice volume), resulting in cycles of emergence and submergence. In limnic systems it finds its most dramatic expression in alternations of lake and playa conditions. Biogenic pelagic oozes such as chalks and the limestones derived from them display variations in the carbonate supplied by planktonic organisms such as coccolithophores and foraminifera, and also record variations in the aeration of bottom waters. Whereas early studies of stratigraphic cyclicity relied mainly on bedding variations visible in the field, present studies are supplementing these with instrumental scans of geochemical, paleontological, and geophysical parameters which yield quantitative curves amenable to time-series analysis; such analysis is, however, limited by problems of distorted time-scales. My own work has been largely concentrated on pelagic systems. In these, the sensitivity of pelagic organisms to climatic-oceanic changes, combined with the sensitivity of botton life to changes in oxygen availability (commonly much more restricted in the Past than now) has left cyclic patterns related to orbital forcing. These systems are further attractive because (1) they tend to offer depositional continuity, and (2) presence of abundant microfossils yields close ties to geochronology. A tantalizing possibility that stratigraphy may yield a record of orbital signals unrelated to climate has turned up in magnetic studies of our Cretaceous core. Magnetic secular variations here carry a strong 39 ka periodicity, corresponding to the theoretical obliquity period of that time - Does the obliquity cycle perhaps have some direct influence on the magnetic field?

Fischer, Alfred G.

1992-01-01

387

GOCE Gravity Gradients in an Orbital Aspect  

NASA Astrophysics Data System (ADS)

This work includes a study of the possibility of the Gravity Field and Steady-State Ocean Circulation Explorer Mission (GOCE) satellite orbit improvement using gravity gradient observations. The orbit improvement is performed by a dedicated software package, called Orbital Computation System (OCS), which is based on the classical least squares method. In an iterative process, the corrections to the initial state vector components of the satellite are estimated, using dynamical models describing gravitational perturbations. An important component implemented in the OCS package is the Cowell 8th order numerical integration procedure, which directly generates the satellite orbit. Taking into account the GOCE real and simulated gravity gradients, different variants of solution of the orbit improvement process were obtained. The improved orbits were compared to the GOCE reference orbits (Precise Science Orbits of the GOCE satellite delivered by the European Space Agency) using the root mean squares (RMS) of the differences between the satellite positions on the improved orbits and on the reference ones. The comparison between the improved orbits and the reference ones was performed with respect to the inertial reference frame (IRF) at J2000.0 epoch. RMS values for the solutions based on the real gravity gradients measurements are at a level of hundreds of kilometers and more. This means that the orbit improvement using the real gravity gradients is ineffective. However, all solutions using the simulated gravity gradients, have RMS values below the threshold determined by RMS values for the computed orbits (without the improvement). The most promising results have been achieved here in the case of improving of short orbital arcs with the lengths from a few to tens of minutes. For these short arcs, RMS values reach the level of centimeters, which is close to the accuracy of Precise Science Orbit of GOCE satellite. Additional research have provided requirements for the effective orbit improvement in terms of the accuracy and spectral content of measured gravity gradients.

Bobojc, Andrzej; Drozyner, Andrzej

2014-05-01

388

Payload/orbiter contamination control requirement study  

NASA Technical Reports Server (NTRS)

A study was conducted to determine and quantify the expected particulate and molecular on-orbit contaminant environment for selected space shuttle payloads as a result of major shuttle orbiter contamination sources. Individual payload susceptibilities to contamination are reviewed. The risk of payload degradation is identified and preliminary recommendations are provided concerning the limiting factors which may depend on operational activities associated with the payload/orbiter interface or upon independent payload functional activities. A basic computer model of the space shuttle orbiter which includes a representative payload configuration is developed. The major orbiter contamination sources, locations, and flux characteristics based upon available data have been defined and modeled.

Bareiss, L. E.; Rantanen, R. O.; Ress, E. B.

1974-01-01

389

ExoMars/TGO Science Orbit Design  

NASA Technical Reports Server (NTRS)

This paper describes the development of the science orbit for the 2016 ESA/NASA collaborative ExoMars/Trace Gas Orbiter (TGO) mission. The initial requirements for the ExoMars/TGO mission simply described the science orbit as circular with a 400 km altitude and a 74 deg inclination. Over the past year, the JPL mission design team worked with the TGO science teams to refine the science orbit requirements and recommend an orbit that would be operationally feasible, easy to maintain, and most important allow the science teams to best meet their objectives.

Long, Stacia; Lyons, Dan; Guinn, Joe; Lock, Rob

2012-01-01

390

A Southern Hemisphere radar meteor orbit survey  

NASA Technical Reports Server (NTRS)

A meteor radar system has been operated on a routine basis near Christchurch, New Zealand, to determine the orbits of Earth-impacting interplanetary dust and meteoroids. The system sensitivity is +13 visual magnitude, corresponding to approximately 100 micron sized meteoroids. With an orbital precision of 2 degrees in angular elements and 10 percent in orbital energy (1/a), the operation yields an average of 1500 orbits daily with a total to date in excess of 10(exp 5). The use of pc's and automated data reduction permit the large orbital data sets we collect to be routinely reduced. Some illustrative examples are presented of the signal formats/processing and the results of data reduction, giving the individual orbital elements and hence the overall distributions. Current studies include the distribution of dust in the inner solar system; the influx of meteoroids associated with near-Earth asteroids; and the orbital structure existing in comet-produced streams.

Baggaley, W. Jack; Steel, Duncan I.; Taylor, Andrew D.

1992-01-01

391

Mission design of a Pioneer Jupiter Orbiter  

NASA Technical Reports Server (NTRS)

The Mission analysis and design work performed in order to define a Pioneer mission to orbit Jupiter is described. This work arose from the interaction with a science advisory 'Mission Definition' team and led to the present mission concept. Building on the previous Jupiter Orbiter-Satellite Tour development at JPL a magnetospheric survey mission concept is developed. The geometric control of orbits which then provide extensive local time coverage of the Jovian system is analyzed and merged with the various science and program objectives. The result is a 'flower-orbit' mission design, yielding three large apoapse excursions at various local times and many interior orbits whose shape and orientation is under continual modification. This orbit design, together with a first orbit defined by delivery of an atmospheric probe, yields a mission of high scientific interest.

Friedman, L. D.; Nunamaker, R. R.

1975-01-01

392

Orbital inflammatory disease in relapsing polychondritis.  

PubMed

Abstract We present a 73-year-old Chinese male with bilateral relapsing, remitting orbital inflammatory disease associated with relapsing polychondritis. He first presented with right orbital inflammation that did not improve despite antibiotic treatment. Computer tomography (CT) of the orbits showed a soft tissue mass along the roof of the orbit, which was biopsied, revealing acute on chronic inflammation. There was complete resolution of his orbital inflammation within 2 weeks of initiating systemic steroid treatment. He subsequently developed recurrent bouts of left orbital inflammation. One year later, he was diagnosed with relapsing polychondritis and subsequently developed multiple myeloma seven years later. Comanagement with a rheumatologist will be helpful to achieve control of the disease with judicious use of immunosuppression. Long-term follow-up of the patient will be necessary to monitor for malignant transformation of the orbital lesion, as well as the development of other hematologic malignancies. PMID:24831308

Teo, Livia; Choo, Chai Teck

2014-08-01

393

Orbital perturbations of low orbiters in a dusty Martian atmosphere  

NASA Astrophysics Data System (ADS)

A study of a low-orbit polar satellite around Mars is carried out using Lagrangian mechanics principles and Lagrange's planetary equations in which both conservative and non-conservative forces are modelled. Our work differs from state-of-the-art Newtonian and Gaussian methods and enhances the modelling of the perturbing potentials arising from areopotential anomalies: atmospheric drag, dust drag, solar radiation pressure, relativistic effects, third-body, and solid-body tides on Mars. Because we are interested in analytical/numerical expressions and results, the Lagrangian method constitutes a more suitable analytical approach than does the traditional Gaussian. The resulting system of equations of motion for the satellite provides the time derivatives of the orbital elements as functions of the gravitational harmonic coefficients and all the perturbing effects we considered. When the time derivatives of the orbital elements are available from satellite tracking observations, the equations can be used in a least-squares estimation process to provide, the gravitational field in terms of harmonic coefficients. To understand the utility of the derived equations of motion, we obtain analytical expressions for the gravitational harmonics of degree and order six. These expressions involve, among other variables, the inclination and eccentricity functions and their time derivatives. In particular, the numerical calculation of high-degree/order eccentricity and inclination functions are known to be numerically unstable. To remove such instabilities, we use an effective and efficient transformation that relates the eccentricity functions to Hansen coefficients, using Bessel functions of the first kind. Similarly, the inclination functions are transformed into hypergeometric series. Analytical and numerical tests show that the transformed inclination and eccentricity functions are remarkably stable up to degree/order eighty. This is very important when the Lagrangian method is used to determine the gravitational field with high accuracy and spatial resolution. We study the effects of atmospheric dust on low orbiters by considering a low velocity "fluid" dust medium containing dust particles of radius 1.25 mum, by deriving a velocity-cube dissipation function that represents the energy density dissipated by the satellite per unit time. We have developed a method for determining a satellite's dust drag coefficient provided that its geometrical shape is known. For example, for a cylindrical satellite, we find that Cd = 4. We also calculate an upper bound to the atmospheric dust density of 8.323 x 10-10 kg m-3 at an altitude of 100 km. Local dust storm-clouds in the range of 800 - 1000 km reduce the semi-major axis from a few centimetres up to a few decimetres per day. Similarly, episodic dust clouds of 10 km in length and at low altitudes (65 - 90 km) result in sub-millimetre per day losses in the semi-major axis. The satellite's mass increase due to dust adhesion is modelled by considering the dust as an aerosol moving in an atmospheric fluid. Adhesion affects the semi-major axis by a few millimetres to a few decimetres per year. Other orbital elements are affected only by insignificant amounts.

Haranas, Ioannis Iraklis

2010-12-01

394

Kalman Orbit Optimized Loop Tracking  

NASA Technical Reports Server (NTRS)

Under certain conditions of low signal power and/or high noise, there is insufficient signal to noise ratio (SNR) to close tracking loops with individual signals on orbiting Global Navigation Satellite System (GNSS) receivers. In addition, the processing power available from flight computers is not great enough to implement a conventional ultra-tight coupling tracking loop. This work provides a method to track GNSS signals at very low SNR without the penalty of requiring very high processor throughput to calculate the loop parameters. The Kalman Orbit-Optimized Loop (KOOL) tracking approach constitutes a filter with a dynamic model and using the aggregate of information from all tracked GNSS signals to close the tracking loop for each signal. For applications where there is not a good dynamic model, such as very low orbits where atmospheric drag models may not be adequate to achieve the required accuracy, aiding from an IMU (inertial measurement unit) or other sensor will be added. The KOOL approach is based on research JPL has done to allow signal recovery from weak and scintillating signals observed during the use of GPS signals for limb sounding of the Earth s atmosphere. That approach uses the onboard PVT (position, velocity, time) solution to generate predictions for the range, range rate, and acceleration of the low-SNR signal. The low- SNR signal data are captured by a directed open loop. KOOL builds on the previous open loop tracking by including feedback and observable generation from the weak-signal channels so that the MSR receiver will continue to track and provide PVT, range, and Doppler data, even when all channels have low SNR.

Young, Lawrence E.; Meehan, Thomas K.

2011-01-01

395

Orbital Magnetization in Periodic Insulators  

NASA Astrophysics Data System (ADS)

Recent years have seen a surge of interest in issues of charge and spin transport in magnetic materials and nanostructures, including anomalous Hall and spin Hall effects. In this context, it is quite surprising that the theory of orbital magnetization has remained in a condition similar to that of the polarization before the early 1990s, when the problem of computing finite polarization changes was solved by the introduction of the Berry-phase theory. The essential difficulty, that the matrix elements of the position operator r are not well-defined in the Bloch representation, could be overcome by reformulating the problem in the Wannier representation. In order to derive an analogue theory for the orbital magnetization, we again work in the Wannier representation and assume a periodic insulator with broken time-reversal symmetry, vanishing (or commensurate) magnetic field, and zero Chern numbers. We show that by replacing the dipole operator r with the circulation operator rxv, only one contribution to the magnetization is found, i.e., the magnetization associated with the internal circulation of bulk-like Wannier functions. The missing contribution arises from net currents carried by the Wannier functions at the boundary of the sample. We prove that both contributions can be expressed as bulk properties in terms of Bloch functions in a gauge-invariant way.ootnotetextT. Thonhauser, Davide Ceresoli, David Vanderbilt, and R. Resta, Phys. Rev. Lett. 95, 137,05 (2005). Our expression for the orbital magnetization is verified by comparing numerical tight-binding calculations for finite and periodic samples. Possible extensions to metals or insulators with non-zero Chern numbers will also be discussed. R. King-Smith and D. Vanderbilt, Phys. Rev. B 47, 1651 (1993).

Thonhauser, Timo

2006-03-01

396

Orbital Space Plane Program Status  

NASA Technical Reports Server (NTRS)

The Orbital Space Plane Program is an integral part of NASA's Integrated Space Transportation Program (ISTP). The ISTP consists of three major programs: Space Shuttle, Orbital Space Plane, and Next Generation Launch Technology. The Orbital Space Plane (OSP) Program will develop a new Crew Transfer Vehicle (CTV) with multipurpose utility for the Agency. The CTV will complement and back up the Space Shuttle by taking crews to and from the International Space Station (ISS), as well as enable a transition path to future reusable launch vehicle systems. In the CTV development cycle, around 2010 it will be used as a Crew Return Vehicle (CRV). The OSP will be launched on an Evolved Expendable Launch Vehicle (EELV). NASA is in the process of establishing Level 1 Requirements and initiating concept studies. Ongoing flight demonstrators will continue, while new flight demonstrator projects will begin. The OSP Program contains two elements: (1) Technology and Demonstrations, and (2) Design, Development, and Production. The OSP Design, Development, and Production element will enter the Formulation Phase in FY03. Per NASA Procedures and Guidelines 7120.5B, the Formulation Phase will be utilized to establish the Program schedule and budget plans. Current budget planning is based on Phase A concept studies being conducted in FY03 and FY04, preliminary design activities conducted in FY04 and FY05, and a Preliminary Design Review in FY05. An OSP full-scale development decision will be made in FY05. At that point, a conclusion to proceed will result in the OSP Program transitioning from the Formulation Phase to the Development Phase.

Dumbacher, Daniel L.

2003-01-01

397

Viking orbiter stereo imaging catalog  

NASA Technical Reports Server (NTRS)

The extremely long missions of the two Viking Orbiter spacecraft produced a wealth of photos of surface features. Many of which can be used to form stereo images allowing the earth-bound student of Mars to examine the subject in 3-D. This catalog is a technical guide to the use of stereo coverage within the complex Viking imaging data set. Since that data set is still growing (January, 1980, about 3 1/2 years after the mission began), a second edition of this catalog is planned with completion expected about November, 1980.

Blasius, K. R.; Vetrone, A. V.; Martin, M. D.

1980-01-01

398

Orbital cysticercosis: A case report  

PubMed Central

A 22 years old male presented to us with a history of lid swelling and chemosis of conjunctiva since 2 days. The patient had a history of convulsions 4 days back and 2 months back. The patient had undergone a CT scan which showed granulomas in temporal and parietal lobes. The patient was started on Anti tuberculosis treatment by the Physician. The Patient underwent USG B scan which revealed cysticercosis cyst in the anterior orbit inferiorly .The patient was treated with albendazole and wysolone for a month. The patient was reviewed after 1 month .The lesion resolved with the treatment both clinically and on USG.

Damani, Mehul; Mehta, Vinod C.; Baile, Rahul B.; Nakwa, Bhalachandra

2012-01-01

399

Orbital debris: A technical assessment  

NASA Technical Reports Server (NTRS)

To acquire an unbiased technical assessment of (1) the research needed to better understand the debris environment, (2) the necessity and means of protecting spacecraft against the debris environment, and (3) potential methods of reducing the future debris hazard, NASA asked the National Research Council to form an international committee to examine the orbital debris issue. The committee was asked to draw upon available data and analyses to: characterize the current debris environment, project how this environment might change in the absence of new measures to alleviate debris proliferation, examine ongoing alleviation activities, explore measures to address the problem, and develop recommendations on technical methods to address the problems of debris proliferation.

Gleghorn, George; Asay, James; Atkinson, Dale; Flury, Walter; Johnson, Nicholas; Kessler, Donald; Knowles, Stephen; Rex, Dietrich; Toda, Susumu; Veniaminov, Stanislav

1995-01-01

400

PHOTOMETRIC ORBITS OF EXTRASOLAR PLANETS  

SciTech Connect

We define and analyze the photometric orbit (PhO) of an extrasolar planet observed in reflected light. In our definition, the PhO is a Keplerian entity with six parameters: semimajor axis, eccentricity, mean anomaly at some particular time, argument of periastron, inclination angle, and effective radius, which is the square root of the geometric albedo times the planetary radius. Preliminarily, we assume a Lambertian phase function. We study in detail the case of short-period giant planets (SPGPs) and observational parameters relevant to the Kepler mission: 20 ppm photometry with normal errors, 6.5 hr cadence, and three-year duration. We define a relevant 'planetary population of interest' in terms of probability distributions of the PhO parameters. We perform Monte Carlo experiments to estimate the ability to detect planets and to recover PhO parameters from light curves. We calibrate the completeness of a periodogram search technique, and find structure caused by degeneracy. We recover full orbital solutions from synthetic Kepler data sets and estimate the median errors in recovered PhO parameters. We treat in depth a case of a Jupiter body-double. For the stated assumptions, we find that Kepler should obtain orbital solutions for many of the 100-760 SPGP that Jenkins and Doyle estimate Kepler will discover. Because most or all of these discoveries will be followed up by ground-based radial velocity observations, the estimates of inclination angle from the PhO may enable the calculation of true companion masses: Kepler photometry may break the 'msin i' degeneracy. PhO observations may be difficult. There is uncertainty about how low the albedos of SPGPs actually are, about their phase functions, and about a possible noise floor due to systematic errors from instrumental and stellar sources. Nevertheless, simple detection of SPGPs in reflected light should be robust in the regime of Kepler photometry, and estimates of all six orbital parameters may be feasible in at least a subset of cases.

Brown, Robert A. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States)], E-mail: rbrown@stsci.edu

2009-09-10

401

Environmental dynamics at orbital altitudes  

NASA Technical Reports Server (NTRS)

The work reported involved the improvement of aerodynamic theory for free molecular and transition flow regimes. The improved theory was applied to interpretation of the dynamic response of objects traveling through the atmosphere. Satellite drag analysis includes analysis methods, atmospheric super rotation effects, and satellite lift effects on orbital dynamics. Transition flow regimes were studied with falling sphere data and errors resulting in inferred atmospheric parameters from falling sphere techniques. Improved drag coefficients reveal considerable error in previous falling sphere data. The drag coefficient has been studied for the entire spectrum of Knudsen Number and speed ratio, with particular emphasis on the theory of the very low-speed ratio regime.

Karr, G. R.

1976-01-01

402

On-Orbit Software Analysis  

NASA Technical Reports Server (NTRS)

The On-Orbit Software Analysis Research Infusion Project was done by Intrinsyx Technologies Corporation (Intrinsyx) at the National Aeronautics and Space Administration (NASA) Ames Research Center (ARC). The Project was a joint collaborative effort between NASA Codes IC and SL, Kestrel Technology (Kestrel), and Intrinsyx. The primary objectives of the Project were: Discovery and verification of software program properties and dependencies, Detection and isolation of software defects across different versions of software, and Compilation of historical data and technical expertise for future applications

Moran, Susanne I.

2004-01-01

403

The Moon Orbits the Sun?!  

NSDL National Science Digital Library

In this activity, students compute the strengths of the gravitational forces exerted on the Moon by the Sun and by the Earth, and demonstrate the actual shape of the Moon's orbit around the Sun. The lesson begins with students' assumptions about the motions of the Moon about the Earth and the Earth about the Sun, and then test their understanding using an experimental apparatus made from a cardboard or plywood disk and rope. This resource is from PUMAS - Practical Uses of Math and Science - a collection of brief examples created by scientists and engineers showing how math and science topics taught in K-12 classes have real world applications.

404

Optimal control during orbital rendezvous  

NASA Astrophysics Data System (ADS)

The paper examines the coplanar rendezvous of a maneuvering spacecraft with a passive spacecraft in a circular orbit. It is assumed that a control acceleration of limited magnitude is imposed on the active spacecraft, and that its direction changes in accordance with a fuel-optimal control law. An analytical solution is sought for the corresponding variational problem in a finite form, with specified constraints on the rendezvous time. An optimal relationship is obtained for changes of the tangent of the angle of the control-acceleration vector in the form of a fractional-linear function of time.

Iablonko, Iu. P.

1982-07-01

405

A Spectroscopic Orbit for Regulus  

NASA Astrophysics Data System (ADS)

We present a radial velocity study of the rapidly rotating B star Regulus that indicates the star is a single-lined spectroscopic binary. The orbital period (40.11 days) and probable semimajor axis (0.35 AU) are large enough that the system is not interacting at present. However, the mass function suggests that the secondary has a low mass (M2>0.30 Msolar), and we argue that the companion may be a white dwarf. Such a star would be the remnant of a former mass donor that was the source of the large spin angular momentum of Regulus itself.

Gies, D. R.; Dieterich, S.; Richardson, N. D.; Riedel, A. R.; Team, B. L.; McAlister, H. A.; Bagnuolo, W. G., Jr.; Grundstrom, E. D.; Štefl, S.; Rivinius, Th.; Baade, D.

2008-08-01

406

Bayesian inference for orbital eccentricities  

NASA Astrophysics Data System (ADS)

Highest posterior density intervals (HPDIs) are derived for the true eccentricities ? of spectroscopic binaries with measured values e ? 0. These yield upper limits when e is below the detection threshold eth and seamlessly transform to upper and lower bounds when e > eth. In the main text, HPDIs are computed with an informative eccentricity prior representing orbital decay due to tidal dissipation. In an appendix, the corresponding HPDIs are computed with a uniform prior and are the basis for a revised version of the Lucy-Sweeney test, with the previous outcome ? = 0 now replaced by an upper limit ?U. Sampling experiments with known prior confirm the validity of the HPDIs.

Lucy, L. B.

2013-03-01

407

Calibration effects on orbit determination  

NASA Technical Reports Server (NTRS)

The effects of charged particle and tropospheric calibrations on the orbit determination (OD) process are analyzed. The calibration process consisted of correcting the Doppler observables for the media effects. Calibrated and uncalibrated Doppler data sets were used to obtain OD results for past missions as well as Mariner Mars 1971. Comparisons of these Doppler reductions show the significance of the calibrations. For the MM'71 mission, the media calibrations proved themselves effective in diminishing the overall B-plane error and reducing the Doppler residual signatures.

Madrid, G. A.; Winn, F. B.; Zielenbach, J. W.; Yip, K. B.

1974-01-01

408

The Orbiting Carbon Observatory (OCO)  

NASA Technical Reports Server (NTRS)

CO2 is the principal human generated driver of climate change. Accurate forecasting of future climate requires an improved understanding of the global carbon cycle and its interaction with the climate system. The Orbiting Carbon Observatory (OCO) will make global, space-based observations of atmospheric CO2 with the precision, resolution, and coverage needed to understand sources and sinks. OCO data will provide critical information for decision makers including the scientific basis for policy formulation, guide for carbon management strategies and treaty monitoring.

Miller, Charles E.

2005-01-01

409

Comet C/2011 W3 (Lovejoy): Orbit Determination, Outbursts, Disintegration of Nucleus, Dust-tail Morphology, and Relationship to New Cluster of Bright Sungrazers  

NASA Astrophysics Data System (ADS)

We describe the physical and orbital properties of C/2011 W3. After surviving perihelion passage, the comet was observed to undergo major physical changes. The permanent loss of the nuclear condensation and the formation of a narrow spine tail were observed first at Malargue, Argentina, on December 20 and then systematically at Siding Spring, Australia. The process of disintegration culminated with a terminal fragmentation event on December 17.6 UT. The postperihelion dust tail, observed for ~3 months, was the product of activity over <2 days. The nucleus' breakup and crumbling were probably caused by thermal stress due to the penetration of the intense heat pulse deep into the nucleus' interior after perihelion. The same mechanism may be responsible for cascading fragmentation of sungrazers at large heliocentric distances. The delayed response to the hostile environment in the solar corona is at odds with the rubble-pile model, since the residual mass of the nucleus, estimated at ~1012 g (equivalent to a sphere 150-200 m across) just before the terminal event, still possessed nontrivial cohesive strength. The high production rates of atomic oxygen, observed shortly after perihelion, are compatible with a subkilometer-sized nucleus. The spine tail—the product of the terminal fragmentation—was a synchronic feature, whose brightest part contained submillimeter-sized dust grains, released at velocities of up to 30 m s-1. The loss of the nuclear condensation prevented an accurate orbital-period determination by traditional techniques. Since the missing nucleus must have been located on the synchrone, whose orientation and sunward tip have been measured, we compute the astrometric positions of this missing nucleus as the coordinates of the points of intersection of the spine tail's axis with the lines of forced orbital-period variation, derived from the orbital solutions based on high-quality preperihelion astrometry from the ground. The resulting orbit gives 698 ± 2 yr for the osculating orbital period, showing that C/2011 W3 is the first member of the expected new, 21st-century cluster of bright Kreutz-system sungrazers, whose existence was predicted by these authors in 2007. From the spine tail's evolution, we determine that its measured tip, populated by dust particles 1-2 mm in diameter, receded antisunward from the computed position of the missing nucleus. The bizarre appearance of the comet's dust tail in images taken only hours after perihelion with the coronagraphs on board the SOHO and STEREO spacecraft is readily understood. The disconnection of the comet's head from the tail released before perihelion and an apparent activity attenuation near perihelion have a common cause—sublimation of all dust at heliocentric distances smaller than about 1.8 solar radii. The tail's brightness is strongly affected by forward scattering of sunlight by dust. From an initially broad range of particle sizes, the grains that were imaged the longest had a radiation-pressure parameter ? ~= 0.6, diagnostic of submicron-sized silicate grains and consistent with the existence of the dust-free zone around the Sun. The role and place of C/2011 W3 in the hierarchy of the Kreutz system and its genealogy via a 14th-century parent suggest that it is indirectly related to the celebrated sungrazer X/1106 C1, which, just as the first-generation parent of C/2011 W3, split from a common predecessor during the previous return to perihelion.

Sekanina, Zdenek; Chodas, Paul W.

2012-10-01

410

The Kepler Project: Mission Update  

NASA Technical Reports Server (NTRS)

Kepler is a Discovery-class mission designed to determine the frequency of Earth-size planets in and near the habitable zone of solar-like stars. The instrument consists of a 0.95 m aperture photometer designed to obtain high precision photometric measurement of > 100,000 stars to search for patterns of transits. The focal plane of the Schmidt-telescope contains 42 CCDs with at total of 95 mega pixels that cover 116 square degrees of sky. The photometer was launched into an Earth-trailing heliocentric orbit on March 6, 2009, finished its commissioning on May 12, and is now in the science operations mode. During the commissioning of the Kepler photometer, data were obtained at a 30 minute cadence for 53,000 stars for 9.7 days. Although the data have not yet been corrected for the presence of systematic errors and artifacts, the data show the presence of hundreds of eclipsing binary stars and variable stars of amazing variety. To provide some estimate of the capability of the photometer, a quick analysis of the photometric precision was made. Analysis of the commissioning data also show transits, occultations and light emitted from the known exoplanet HAT-P7b. The data show a smooth rise and fall of light: from the planet as it orbits its star, punctuated by a drop of 130 +/- 11 ppm in flux when the planet passes behind its star. We interpret this as the phase variation of the dayside thermal emission plus reflected light from the planet as it orbits its star and is occulted. The depth of the occultation is similar in amplitude to that expected from a transiting Earth-size planet and demonstrates that the Mission has the precision necessary to detect such planets.

Borucki, William J.; Koch, David G.

2009-01-01

411

A method for classifying orbits near asteroids  

NASA Astrophysics Data System (ADS)

A method for classifying orbits near asteroids under a polyhedral gravitational field is presented, and may serve as a valuable reference for spacecraft orbit design for asteroid exploration. The orbital dynamics near asteroids are very complex. According to the variation in orbit characteristics after being affected by gravitational perturbation during the periapsis passage, orbits near an asteroid can be classified into 9 categories: (1) surrounding-to-surrounding, (2) surrounding-to-surface, (3) surrounding-to-infinity, (4) infinity-to-infinity, (5) infinity-to-surface, (6) infinity-to-surrounding, (7) surface-to-surface, (8) surface-to-surrounding, and (9) surface-to-infinity. Assume that the orbital elements are constant near the periapsis, the gravitation potential is expanded into a harmonic series. Then, the influence of the gravitational perturbation on the orbit is studied analytically. The styles of orbits are dependent on the argument of periapsis, the periapsis radius, and the periapsis velocity. Given the argument of periapsis, the orbital energy before and after perturbation can be derived according to the periapsis radius and the periapsis velocity. Simulations have been performed for orbits in the gravitational field of 216 Kleopatra. The numerical results are well consistent with analytic predictions.

Wang, Xian-Yu; Gong, Sheng-Ping; Li, Jun-Feng

2014-05-01

412

[Clinical and neuroradiological diagnostics of orbital tumors].  

PubMed

Exophthalmus is the leading sign of space-occupying lesions of the orbit. Patients may further present with lid swelling, impaired ocular motility and optic neuropathy including a relative afferent pupillary defect, compressive optic disc edema or optic atrophy. Orbital tumors can be classified into various categories depending on the etiology, as lymphoproliferative lesions (in particular non-Hodgkin's lymphoma as the most common malignant orbital tumor of adulthood), optic nerve and meningeal lesions, lacrimal gland lesions, secondary orbital tumors which extend to the orbit from neighboring structures and metastases. Slightly less common are vasculogenic and cystic lesions including cavernous hemangioma as the most common benign orbital tumor of adulthood and dermoid cysts as the most common benign orbital tumor of childhood. Rhabdomyosarcoma is the most common malignant orbital tumor of childhood but has a low total incidence. Orbital tumors might not only cause symptoms like pain, diplopia and loss of visual acuity but may also lead to esthetically disfiguring changes. Particular attention should be paid to underlying systemic diseases and generalized tumor diseases. This article illustrates the approach to a detailed clinical and neuroradiological assessment which is mandatory for the care of orbital tumor patients. PMID:21695605

Poloschek, C M; Lagrèze, W A; Ridder, G J; Hader, C

2011-06-01

413

Gravitational orbits in one dimension  

NASA Astrophysics Data System (ADS)

The analytic solution of a body falling an arbitrary distance toward a gravitational source is presented. This problem has apparently received little attention in textbooks. The solution can be extended smoothly through the singularity at the origin to form a class of trajectories that we call singular orbits. Trajectories in phase space have singular branches, yet cycle in a finite time. We calculate the period of oscillation about the singularity confirming that the singular orbits obey Kepler's third law. Viewed as geodesics in a Newtonian 1+1 spacetime, the geodesic deviation equation is derived and solved analytically, providing an excellent example of curvature physics in Newtonian spacetime. The results are used to estimate the duration during which a freely falling local frame can be considered inertial. A numerical investigation with damping included shows that a final state is reached in which the particle is confined to the origin, but acquires infinite speed during each pass. We show via some examples, the pedagogical applications of the solution.

McCall, Martin

2006-12-01

414

Superfluid Helium Orbital Resupply Coupling  

NASA Technical Reports Server (NTRS)

The resupply of superfluid helium to satellites and other space-based experiment packages can increase the useful longevity of these devices far beyond their present life expectancies which are many times determined by the supply of helium coolant. The transfer of superfluid helium to spacecraft in space will require a reusable coupling that functions at 1.8 Kelvin with little heat leak and low pressure drop. Moog has designed the Helium Resupply Coupling to meet these operational requirements. Initially, the coupling manual mode operation will be demonstrated on orbit by an EVA crew member during the Space Shuttle borne Superfluid Helium On-Orbit Transfer (SHOOT) experiment. The ultimate application will use robotic (automatic) coupling operation to which the present design readily adapts. The utilization of Moog's exclusive Rotary Shut-Off (RSO) technology in the development of the Superfluid Helium Resupply Coupling is described. The coupling not only performs the function of a flow control valve and disconnect but also provides adequate safety features for a shuttle launched man-rated payload. In addition, the coupling incorporates the necessary features to provide the high thermal isolation of the internal flow path from the external environment.

Ryder, M. O.; Morash, D. H.; Schoenberg, R. J.

1989-01-01

415

Dexterous Orbital Servicing System (DOSS)  

NASA Technical Reports Server (NTRS)

The Dexterous Orbiter Servicing System (DOSS) is a dexterous robotic spaceflight system that is based on the manipulator designed as part of the Flight Telerobotics Servicer program for the Space Station Freedom and built during a 'technology capture' effort that was commissioned when the FTS was cancelled from the Space Station Freedom program. The FTS technology capture effort yielded one flight manipulator and the 1 g hydraulic simulator that had been designed as an integrated test tool and crew trainer. The DOSS concept was developed to satisfy needs of the telerobotics research community, the space shuttle, and the space station. As a flight testbed, DOSS would serve as a baseline reference for testing the performance of advanced telerobotics and intelligent robotics components. For shuttle, the DOSS, configured as a movable dexterous tool, would be used to provide operational flexibility for payload operations and contingency operations. As a risk mitigation flight demonstration, the DOSS would serve the International Space Station to characterize the end to end system performance of the Special Purpose Dexterous Manipulator performing assembly and maintenance tasks with actual ISSA orbital replacement units. Currently, the most likely entrance of the DOSS into spaceflight is a risk mitigation flight experiment for the International Space Station.

Price, Charles R.; Berka, Reginald B.; Chladek, John T.

1994-01-01

416

Anteromedial Approach to the Orbit  

PubMed Central

This study evaluated the surgical results of the anteromedial approach for treatment of orbital lesions in 16 patients. Pre- and postoperatively, all patients underwent a complete physical examination focusing on the head and neck area including a thorough ophthalmologic evaluation, computerized tomography, and magnetic resonance imaging. The surgical approach was limited to a medial orbitotomy in five patients; the remaining 11 patients underwent a medial orbitotomy combined with an external sphenoethmoidectomy. The tumor was removed completely without damaging the intraorbital neurovascular structures in all but one patient whose recurrent clival chordoma extended beyond the limits of an extracranial approach. Fibro-osseous lesions, cavernous hemangiomas, and dermoid cysts were the most common pathologies. The follow-up ranged from 18 to 48 months, and no patient has shown evidence of a recurrence. One patient with a clival chordoma received radiation therapy. The lateral nasal skin incision healed with acceptable cosmetic results. The anteromedial approach to the orbit provides a wider working space and direct exposure while protecting neurovascular structures. ImagesFigure 1Figure 2Figure 3

Deda, Haluk; Ugur, Hasan Caglar; Yorulmaz, Irfan; Kucuk, Babur

2001-01-01

417

Safety in earth orbit study. Volume 4: Space shuttle orbiter: Safety requirements and guidelines on-orbit phase  

NASA Technical Reports Server (NTRS)

Safety requirements and guidelines are listed for the space shuttle orbiter and for its interface with other vehicles. The requirements and guidelines are specific to the hazards and emergencies in earth orbit. The requirements and guidelines for the orbiter are those with respect to vehicle design, safety devices, warning devices, operational procedures, and residual hazards. The requirements and guidelines for interface with the space station, upper stage vehicles, and sortie payloads are imposed on these vehicles to ensure the safety of the shuttle orbiter. The rationale for the safety requirements and guidelines is also discussed.

1972-01-01

418

Determination and prediction of Magellan's orbit  

NASA Technical Reports Server (NTRS)

The Magellan spacecraft has been systematically mapping the surface of Venus since September 15, 1990, using a synthetic aperture radar. The spacecraft orbit about Venus is nearly polar, with an orbital period of 3.26 hours and periapsis altitude of 295 km. The radiometric measurements and the data reduction method used to determine and predict the spacecraft state are described. Orbit determination and prediction results are given for the first 146 days of mapping (through February 8, 1991, 60 percent of the first rotation of Venus). Orbit accuracy requirements of 150 meters in the radial position, and 1 km in the along-track and cross-track positions are shown to be met, but with exceptions. All error requirements were exceeded during a combined period of limited in-plane orbit observability due to earth-orbit relative geometry, and increased measurement noise due to superior conjunction.

Engelhardt, D. B.; Mcnamee, J. B.; Wong, S. K.; Bonneau, F. G.; Graat, E. J.; Haw, R. J.; Kronschnabl, G. R.; Ryne, M. S.

1991-01-01

419

Stable spatial orbits around collinear libration points  

NASA Astrophysics Data System (ADS)

A technique of generation of spatial periodic solutions to the restricted circular three-body problem from periodic orbits of the planar problem has been used for the families of orbits around collinear libration points L 1 and L 2. Developing the families obtained at the 1: 1 resonance, we have obtained stable solutions both in the Earth-Moon system and in the Sun-Earth system. Of course, the term “around the libration point” is rather conventional; the obtained orbits become more similar to the orbits around the smaller attracting body. The further development of the family of orbits “around” the libration point L 2 in the Sun-Earth system made it possible to find the orbits satisfying the new, much more rigorous constraints on cooling the spacecraft of the Millimetron project.

Kreisman, B. B.

2010-06-01

420

Ferroelectric control of orbital occupancy in manganites  

NASA Astrophysics Data System (ADS)

Recent successful fabrication of epitaxial and coherent ferroelectric/manganite interfaces makes it possible to dynamically control charge and spin in manganites [1]. We demonstrate with ab initio calculations that in this system, d-orbital occupancies of the interfacial Mn atom can also be modulated by flipping the ferroelectric polarization (i.e. flippable orbital polarization). The underlying mechanism is the structural distortions of the oxygen octahedron and the Mn atom inside induced by the ferroelectric polarization. The in-plane orbital dx^2-y^2 is stablized by rumpling in MnO2 layers, while the Jahn-Teller distortion (c/a>1) favors the out-of-plane orbital d3z^2-r^2. This ferroelectric control of orbital occupancy serves as a new approach separate from strain for engineering orbital orderings in transition metal oxides. [4pt] [1] C.A.F.Vaz et al., Phys. Rev. Lett. 104, 127202 (2010)

Chen, Hanghui; Ismail-Beigi, Sohrab

2012-02-01

421

Extended duration Orbiter life support definition  

NASA Technical Reports Server (NTRS)

Extending the baseline seven-day Orbiter mission to 30 days or longer and operating with a solar power module as the primary source for electrical power requires changes to the existing environmental control and life support (ECLS) system. The existing ECLS system imposes penalties on longer missions which limit the Orbiter capabilities and changes are required to enhance overall mission objectives. Some of these penalties are: large quantities of expendables, the need to dump or store large quantities of waste material, the need to schedule fuel cell operation, and a high landing weight penalty. This paper presents the study ground rules and examines the limitations of the present ECLS system against Extended Duration Orbiter mission requirements. Alternate methods of accomplishing ECLS functions for the Extended Duration Orbiter are discussed. The overall impact of integrating these options into the Orbiter are evaluated and significant Orbiter weight and volume savings with the recommended approaches are described.

Kleiner, G. N.; Thompson, C. D.

1978-01-01

422

RHIC BPM system average orbit calculations  

SciTech Connect

RHIC beam position monitor (BPM) system average orbit was originally calculated by averaging positions of 10000 consecutive turns for a single selected bunch. Known perturbations in RHIC particle trajectories, with multiple frequencies around 10 Hz, contribute to observed average orbit fluctuations. In 2006, the number of turns for average orbit calculations was made programmable; this was used to explore averaging over single periods near 10 Hz. Although this has provided an average orbit signal quality improvement, an average over many periods would further improve the accuracy of the measured closed orbit. A new continuous average orbit calculation was developed just prior to the 2009 RHIC run and was made operational in March 2009. This paper discusses the new algorithm and performance with beam.

Michnoff,R.; Cerniglia, P.; Degen, C.; Hulsart, R.; et al.

2009-05-04

423

Precise Method of Orbit Height Determination  

NASA Astrophysics Data System (ADS)

The problem of satellite orbit determination is a very important one, you can determine the orbit height of a low Earth orbiting (LEO) artificial satellite by using the satellite's apparent travel when the satellite appears to be near your local zenith, Or for most precise between two points of observation in earth. By using the determined orbit height, you can also determine the approximate orbit period of the satellite, this method takes advantage of the fact that the satellite's true velocity can be seen when it is nearly overhead. This paper illustrate how to obtain the height of the satellite using two observers method and by using MATLAB program then comparing this method with one observer method and illustrating how to increase the accuracy and take the measurement not limited to the local zenith only, but to any place of the orbit if you have an estimated period time for the satellite also these calculations depends on the data from NASA site.

Elbanna, Ahmed

424

Orbital lymphomas: Clinical and radiological features.  

PubMed

The purpose of this prospective study was to evaluate the clinical and radiological features of a consecutive series of orbital lymphomas in two Institutions in the North West of Italy. A prospective study was performed of all cases of diagnosed orbital lymphomas. Data on patient demographics, symptoms and clinical findings, histological type of lymphoma, site of lesion, imaging, and systemic involvement were recorded in each case. The mean age of the enrolled 20 patients was 63.65 years. Most orbital lymphomas were located in the superior-lateral quadrant. Superior rectus muscle was the most frequently involved orbital structure. Most patients were affected by extranodal marginal-zone lymphomas. The diagnosis of orbital lymphomas may be challenging, because these neoplasms present few specific features. Although not typically performed by the maxillofacial surgeon, an understanding of the staging process is crucial for multidisciplinary management of orbital lymphomas. PMID:24051193

Gerbino, Giovanni; Boffano, Paolo; Benech, Rodolfo; Baietto, Federico; Gallesio, Cesare; Arcuri, Francesco; Benech, Arnaldo

2014-07-01

425

Orbit determination by range-only data.  

NASA Technical Reports Server (NTRS)

The determination of satellite orbits for use in geodesy using range-only data has been examined. A recently developed recursive algorithm for rectification of the nominal orbit after processing each observation has been tested. It is shown that when a synchronous satellite is tracked simultaneously with a subsynchronous geodetic target satellite, the orbits of each may be readily determined by processing the range information. Random data errors and satellite perturbations are included in the examples presented.

Duong, N.; Winn, C. B.

1973-01-01

426

Extended Duration Orbiter - Meeting the challenge  

NASA Technical Reports Server (NTRS)

The paper overviews the Extended Duration Orbiter (EDO) program designed to provide an on-orbit stay capability of 16 days using the Orbiter Vehicle OV-102. Special attention is given to the EDO's subsystems and substructures, including the cryogenic pallet, the cryogenic storage tanks, the cryogenic solenoid valves, the regenerable carbon dioxide removal system, and the waste collection system. The EDO program will start with the STS-50 U.S. Microgravity Lab mission planned for June 1992.

Saucier, D. R.

1992-01-01

427

Imaging of the normal and pathological orbit  

Microsoft Academic Search

.   Computerized techniques (CT and MRI) allow precise delineation of orbital anatomy and abnormalities. Orbital tumors are nicely\\u000a depicted by these methods; various examples are illustrated in this article, with discussion of the respective impact of CT\\u000a and MRI. Orbital inflammation and foreign bodies usually represent radiologic emergencies, prompting use of CT (frequently)\\u000a or MRI (occasionally). Digital subtraction angiography (DSA)

B. Duvoisin; F. E. Zanella; K. W. Sievers

1998-01-01

428

Orbital Decompression in Thyroid Eye Disease  

PubMed Central

Though enlargement of the bony orbit by orbital decompression surgery has been known for about a century, surgical techniques vary all around the world mostly depending on the patient's clinical presentation but also on the institutional habits or the surgeon's skills. Ideally every surgical intervention should be tailored to the patient's specific needs. Therefore the aim of this paper is to review outcomes, hints, trends, and perspectives in orbital decompression surgery in thyroid eye disease regarding different surgical techniques.

Fichter, N.; Guthoff, R. F.; Schittkowski, M. P.

2012-01-01

429

Orbital Debris and NASA's Measurement Program  

NASA Astrophysics Data System (ADS)

Since the launch of Sputnik in 1957, the number of manmade objects in orbit around the Earth has dramatically increased. The United States Space Surveillance Network (SSN) tracks and maintains orbits on over nine thousand objects down to a limiting diameter of about ten centimeters. Unfortunately, active spacecraft are only a small percentage ( ~ 7%) of this population. The rest of the population is orbital debris or ``space junk" consisting of expended rocket bodies, dead payloads, bits and pieces from satellite launches, and fragments from satellite breakups. The number of these smaller orbital debris objects increases rapidly with decreasing size. It is estimated that there are at least 130,000 orbital debris objects between one and ten centimeters in diameter. Most objects smaller than 10 centimeters go untracked! As the orbital debris population grows, the risk to other orbiting objects, most importantly manned space vehicles, of a collision with a piece of debris also grows. The kinetic energy of a solid 1 cm aluminum sphere traveling at an orbital velocity of 10 km/sec is equivalent to a 400 lb. safe traveling at 60 mph. Fortunately, the volume of space in which the orbiting population resides is large, collisions are infrequent, but they do occur. The Space Shuttle often returns to earth with its windshield pocked with small pits or craters caused by collisions with very small, sub-millimeter-size pieces of debris (paint flakes, particles from solid rocket exhaust, etc.), and micrometeoroids. To get a more complete picture of the orbital-debris environment, NASA has been using both radar and optical techniques to monitor the orbital debris environment. This paper gives an overview of the orbital debris environment and NASA's measurement program.

Africano, J. L.; Stansbery, E. G.

2002-05-01

430

Space Shuttle orbiter approach and landing test  

NASA Technical Reports Server (NTRS)

The Approach and Landing Test Program consisted of a series of steps leading to the demonstration of the capability of the Space Shuttle orbiter to safely approach and land under conditions similar to those planned for the final phases of an orbital flight. The tests were conducted with the orbiter mounted on top of a specially modified carrier aircraft. The first step provided airworthiness and performance verification of the carrier aircraft after modification. The second step consisted of three taxi tests and five flight tests with an inert unmanned orbiter. The third step consisted of three mated tests with an active manned orbiter. The fourth step consisted of five flights in which the orbiter was separated from the carrier aircraft. For the final two flights, the orbiter tail cone was replaced by dummy engines to simulate the actual orbital configuration. Landing gear braking and steering tests were accomplished during rollouts following the free flight landings. Ferry testing was integrated into the Approach and Landing Test Program to the extent possible. In addition, four ferry test flights were conducted with the orbiter mated to the carrier aircraft in the ferry configuration after the free-flight tests were completed.

1978-01-01

431

Payload/orbiter contamination control assessment support  

NASA Technical Reports Server (NTRS)

The development and use is described of a basic contamination mathematical model of the shuttle orbiter which incorporates specific shuttle orbiter configurations and contamination sources. These configurations and sources were evaluated with respect to known shuttle orbiter operational surface characteristics and specific lines-of-sight which encompass the majority of viewing requirements for shuttle payloads. The results of these evaluations are presented as summary tables for each major source. In addition, contamination minimization studies were conducted and recommendations are made, where applicable, to support the shuttle orbiter design and operational planning for those sources which were identified to present a significant contamination threat.

Rantanen, R. O.; Ress, E. B.

1975-01-01

432

Quantum localization on classical periodic orbits  

SciTech Connect

Eigenfunctions of classically chaotic systems concentrated on periodic orbits are studied. Individual eigenstates localized on these orbits persist even as the orbit becomes highly unstable. In this regime, the scar intensity is not concentrated on individual eigenstates, but is shared by several of them which cluster together in energy. The average energy of each cluster is found to be in good agreement with semiclassical quantization at all energies. The phase space structure of members of each group of eigenstates is compared to the classical invariant sets associated with the orbits.

Leboeuf, P. (Inst. de Physique Nucle'aire, Orsay (France)); Meredith, D.C. (Univ. of New Hampshire, Durham (United States)); Saraceno, M. (Comision Nacional de Energia Atomica, Buenos Aires (Argentina))

1991-06-01

433

On-orbit coldwelding: Fact or friction?  

NASA Technical Reports Server (NTRS)

A study into the potential of on-orbit coldwelding occurring was completed. No instances of cold welding were found during deintegration and subsequent testing and analysis of LDEF hardware. This finding generated wide interest and indicated the need to review previous on-orbit coldwelding experiments and on-orbit spacecraft anomalies to determine whether the absence of coldwelding on LDEF was to be expected. Results show that even though there have been no documented cases of significant on-orbit coldwelding events occurring, precautions should be taken to ensure that neither coldwelding nor galling occurs in the space or prelaunch environment.

Dursch, Harry; Spear, Steve

1992-01-01

434

SCIAMACHY In-orbit Operations until 2013  

NASA Astrophysics Data System (ADS)

In 2010 ENVISAT enters its next mission extension phase when a manoeuvre transfers the plat-form from its nominal into a modified orbit. This modified orbit is not only characterized by the lower altitude but also by slightly drifting parameters such as e.g. the inclination or the Mean Local Solar Time at ascending node crossing. Thus all SCIAMACHY measurements requiring an accurate pointing knowledge are affected. How the line-of-sight evolves along the orbit de-pends on orbit altitude and orbital period. Therefore adjustments to SCIAMACHY's on-board instrument configuration are necessary reflecting this orbit chance. Based on a detailed analysis simulating SCIAMACHY operations in the modified orbit until the end of 2013, the impacts on nadir, limb and solar and lunar occultation measurements when orbiting the Earth at a reduced altitude was studied. By modifying SCIAMACHY's configuration these impacts can be compensated for. Thus the current performance of instrument operations, including the pointing knowledge, can be maintained. It ensures acquisition of high quality measurement data for the entire duration of the mission. This presentation describes how the instrument will be configured for achieving successful operations until the end of 2013. In addition a brief outlook is given how the drifting modified orbit may impact an operations phase even beyond 2013 and potential corrective countermeasures.

Gottwald, Manfred; Krieg, Eckhart; Lichtenberg, Günter; Noël, Stefan; Bramstedt, Klaus; Bovensmann, Heinrich

435

Orbit stability of the ALS storage ring  

SciTech Connect

The Advanced Light Source (ALS) storage ring, a synchrotron light source of the third generation, is specified to maintain its electron orbit stable within one tenth of the rms beam size. In the absence of a dedicated orbit feed-back system, several orbit-distorting effects were investigated, aided by a new interactive simulation tool, the code TRACY V. The effort has led to a better understanding of the behavior of a variety of accelerator subsystems and in consequence produced a substantial improvement in day-to-day orbit stability.

Keller, R.; Nishimura, H.; Biocca, A. [and others

1997-05-01

436

Nebraska Astronomy Applet Project: Planetary Orbit Simulator  

NSDL National Science Digital Library

This simulation illustrates the physics of planetary orbits. The user can control the size and orbital path of the orbit. Each of Kepler's three laws and aspects of Newton's Law are each demonstrated. Velocity and acceleration vectors can be displayed, as well as the axes of the orbit. Instructor resources are available including student manuals, assessment materials, and a list of the assumptions used. This resource is part of a larger collection of online labs for introductory astronomy.See Related Materials for a link to the full collection.

Lee, Kevin M.

2007-12-20

437

Numerical Mean Element Orbital Analysis with Morbiter  

NASA Technical Reports Server (NTRS)

The Morbiter software numerically averages an osculating orbit s equations of motion (EOM) to arrive at the mean orbit s EOMs, which are then numerically propagated to obtain the long-term orbital ephemerides. The long-term evolution characteristics, and stability, of an orbit are best characterized using a mean element propagation of the perturbed, two-body variational equations of motion. The average process eliminates short period terms, leaving only secular and long period effects. Doing this avoids the Fourier series expansions and truncations required by the traditional analytic methods.

Ely, Todd A.

2010-01-01

438

Orbital Compass Model in a Checkerboard Lattice  

NASA Astrophysics Data System (ADS)

The orbital compass model in a checkerboard lattice is studied. There is a competition between the interaction for the z component of the orbital pseudo-spin along the vertical/horizontal direction and the interaction for the x component along the diagonal direction in a checkerboard lattice. In a frustration point where the two interactions compete with each other, a macroscopic number of the orbital pseudo-spin configurations are degenerated in the classical grounds state. This degeneracy is lifted by the thermal and quantum fluctuations and the z component long range order is realized. The tricritical point appears due to the coexistence of the orbital frustration and the geometrical frustration.

Nasu, Joji; Ishihara, Sumio

2011-09-01

439

Determination of GPS orbits to submeter accuracy  

NASA Technical Reports Server (NTRS)

Orbits for satellites of the Global Positioning System (GPS) were determined with submeter accuracy. Tests used to assess orbital accuracy include orbit comparisons from independent data sets, orbit prediction, ground baseline determination, and formal errors. One satellite tracked 8 hours each day shows rms error below 1 m even when predicted more than 3 days outside of a 1-week data arc. Differential tracking of the GPS satellites in high Earth orbit provides a powerful relative positioning capability, even when a relatively small continental U.S. fiducial tracking network is used with less than one-third of the full GPS constellation. To demonstrate this capability, baselines of up to 2000 km in North America were also determined with the GPS orbits. The 2000 km baselines show rms daily repeatability of 0.3 to 2 parts in 10 to the 8th power and agree with very long base interferometry (VLBI) solutions at the level of 1.5 parts in 10 to the 8th power. This GPS demonstration provides an opportunity to test different techniques for high-accuracy orbit determination for high Earth orbiters. The best GPS orbit strategies included data arcs of at least 1 week, process noise models for tropospheric fluctuations, estimation of GPS solar pressure coefficients, and combine processing of GPS carrier phase and pseudorange data. For data arc of 2 weeks, constrained process noise models for GPS dynamic parameters significantly improved the situation.

Bertiger, W. I.; Lichten, S. M.; Katsigris, E. C.

1988-01-01

440

International Space Station in Orbit  

NASA Technical Reports Server (NTRS)

This image of the International Space Station (ISS) was photographed by one of the crewmembers of the STS-105 mission from the Shuttle Orbiter Discovery after separating from the ISS. The STS-105 mission was the 11th ISS assembly flight and its goals were the rotation of the ISS Expedition Two crew with Expedition Three crew, and the delivery of supplies utilizing the Italian-built Multipurpose Logistic Module (MPLM) Leonardo. Aboard Leonardo were six resupply stowage racks, four resupply stowage supply platforms, and two new scientific experiment racks, EXPRESS (Expedite the Processing of Experiments to the Space Station) Racks 4 and 5, which added science capabilities to the ISS. Another payload was the Materials International Space Station Experiment (MISSE), which included materials and other types of space exposure experiments mounted on the exterior of the ISS.

2001-01-01

441

Mars Reconnaissance Orbiter Wrapper Script  

NASA Technical Reports Server (NTRS)

The MRO OLVM wrapper script software allows Mars Reconnaissance Orbiter (MRO) sequence and spacecraft engineers to rapidly simulate a spacecraft command product through a tool that simulates the onboard sequence management software (OLVM). This script parses sequence files to determine the appropriate time boundaries for the sequence, and constructs the script file to be executed by OLVM to span the entirety of the designated sequence. It then constructs script files to be executed by OLVM, constructs the appropriate file directories, populates these directories with needed input files, initiates OLVM to simulate the actual command product that will be sent to the spacecraft, and captures the results of the simulation run to an external file for later review. Additionally, the tool allows a user to manually construct the script, if desired, and then execute the script with a simple command line.

Gladden, Roy; Fisher, Forest; Khanampornpan, Teerapat

2008-01-01

442

Airbreathing Acceleration Toward Earth Orbit  

SciTech Connect

As flight speed increases, aerodynamic drag rises more sharply than the availability of atmospheric oxygen. The ratio of oxygen mass flux to dynamic pressure cannot be improved by changing altitude. The maximum possible speed for airbreathing propulsion is limited by the ratio of air capture area to vehicle drag area, approximately Mach 6 at equal areas. Simulation of vehicle acceleration shows that the use of atmospheric oxygen offers a significant potential for minimizing onboard consumables at low speeds. These fundamental calculations indicate that a practical airbreathing launch vehicle would accelerate to near steady-state speed while consuming only onboard fuel, then transition to rocket propulsion. It is suggested that an aircraft carrying a rocket-propelled vehicle to approximately Mach 5 could be a realistic technical goal toward improving access to orbit.

Whitehead, J C

2007-05-09

443

International Space Station in Orbit  

NASA Technical Reports Server (NTRS)

This image of the International Space Station (ISS) was photographed by one of the crewmembers of the STS-105 mission from the Shuttle Orbiter Discovery after deparating from the ISS. The STS-105 mission was the 11th ISS assembly flight and its goals were the rotation of the ISS Expedition Two crew with the Expedition Three crew, and the delivery of supplies utilizing the Italian-built Multipurpose Logistics Module (MPLM) Leonardo. Aboard Leonardo were six resupply stowage racks, four resupply stowage supply platforms, and two new scientific experiment racks, EXPRESS (Expedite the Processing of Experiments to the Space Station) Racks 4 and 5, which added science capabilities to the ISS. Another payload was the Materials International Space Station Experiment (MISSE), which included materials and other types of space exposure experiments mounted on the exterior of the ISS.

2001-01-01

444

CCD observations of orbital debris  

NASA Technical Reports Server (NTRS)

A portable 31 cm aperture f/1.3 Schmidt telescope with a CCD sensor at the prime focus has been designed and constructed to carry out photometric studies of earth-orbiting debris. When operated in the time delay integration mode in which the readout rate is matched to the predicted motion of the satellite, this system reaches a limiting diameter of about 10 cm for particles at 400 km height and albedo 0.1. It is used for statistical studies of phase angle effects and for swarm-to-swarm albedo differences between several selected debris groups which include the Cosmos 1275, Cosmos 1375, Landsat 1, Landsat 3, NOAA 3, Nimbus 4, Solwind, and Spot-1/Viking groups.

Henize, Karl G.; O'Neill, Christine A.; Mulrooney, Mark K.

1990-01-01

445

A Mercury orbiter mission design  

NASA Technical Reports Server (NTRS)

The paper presents the results of the first stage of a Mercury Orbiter Mission Concept Definition study originated by NASA, with emphasis on a proposed end-to-end mission scenario. The science rationale and the strawman payload are presented, along with the spacecraft design based on a novel use of conventional technology that eliminates the need for high-cost high-risk technology development. A mission scenario demonstrating the capability of conducting desired science investigations is addressed. It is shown that complete imaging coverage of the planet at 1-km or better resolution, and with at least three different phase angles, is possible. Focus is placed on launch period analysis, mission performance, and mission opportunities.

Yen, Chen-Wan L.; Collins, David H.; Meyer, Scott A.

1989-01-01

446

Phonons with orbital angular momentum  

SciTech Connect

Ion accoustic waves or phonon modes are studied with orbital angular momentum (OAM) in an unmagnetized collissionless uniform plasma, whose constituents are the Boltzmann electrons and inertial ions. For this purpose, we have employed the fluid equations to obtain a paraxial equation in terms of ion density perturbations and discussed its Gaussian beam and Laguerre-Gauss (LG) beam solutions. Furthermore, an approximate solution for the electrostatic potential problem is presented, allowing to express the components of the electric field in terms of LG potential perturbations. The energy flux due to phonons is also calculated and the corresponding OAM is derived. Numerically, it is shown that the parameters such as azimuthal angle, radial and angular mode numbers, and beam waist, strongly modify the profiles of the phonon LG potential. The present results should be helpful in understanding the phonon mode excitations produced by Brillouin backscattering of laser beams in a uniform plasma.

Ayub, M. K. [Theoretical Plasma Physics Division, PINSTECH, P. O. Nilore, Islamabad (Pakistan); National Centre for Physics, Shahdra Valley Road, Quaid-i-Azam University Campus, Islamabad 44000 (Pakistan); Ali, S. [National Centre for Physics, Shahdra Valley Road, Quaid-i-Azam University Campus, Islamabad 44000 (Pakistan); Mendonca, J. T. [IPFN, Instituto Superior Tecnico, Av. Rovisco Pais 1, 1049-001 Lisboa (Portugal)

2011-10-15

447

A remotely controlled orbiting retriever  

NASA Technical Reports Server (NTRS)

A preliminary design effort was recently carried out to investigate methods of removing a certain class of space objects from Shuttle type orbits. Specifically, expired satellites, upper stages, and other objects of potential danger to the Shuttle are the targets of the study. The Trash Remover and Satellite Hauler (TRASH-1) design effort was broken into several disciplines: mission analysis, systems engineering, dynamics and control, power, thermal, and propulsion. A basic requirements is that TRASH-1 go up in the Shuttle. It must be reusable and capable of disposing of more than one item per mission for cost effectiveness. These requirements imply TRASH-1 should use current technology, be modular in design, and be relatively maneuverable. In order to maximize utility, it should be able to both capture and deorbit objects. The design was a basic bus with attachable modules which can either capture or deorbit, depending on the module.

Kaplan, M. H.

1985-01-01

448

Osteoradionecrosis of the exenterated orbit.  

PubMed

Abstract Osteoradionecrosis (ORN) occurs in an estimated 2% of head and neck-irradiated patients. It is seen most commonly in the mandible with other reported sites including the maxilla, temporal bone, clavicle, and vertebrae. It is defined as an area of exposed devitalised irradiated bone, with failure to heal during a period of at least 3 months, in the absence of local neoplastic disease. We report 2 cases of ORN following postoperative radiotherapy given to patients who had undergone an orbital exenteration. ORN can develop spontaneously in one-third of cases, although in the majority of patients, it is induced by secondary trauma. Radiotherapy induces an endarteritis in the small blood vessels of bone, thus favouring the generation of small thrombi that obliterate the vascular lumen and interrupt tissue perfusion. Likewise, irradiation impairs the function of osteoblasts, manifesting as osteopenia, with impairment of the repair and remodelling capacity of bone. Prior radiation exposure can thus decrease bone vascularity and injure its reserve reparative capacity. It is important to differentiate ORN from local recurrence of malignancy, bone metastasis, radiation-induced sarcoma, and infection. CT and MRI are effective diagnostic tools. Clinical management of ORN is complex and unsatisfactory. Treatment remains difficult, and prevention is paramount. A history of radiotherapy should alert clinicians to detect bone exposure or excessively prolonged socket healing. Early diagnosis with a high index of suspicion can achieve higher control rates with conservative management. Our case series reports a rare, previously unreported, but important complication of radiation therapy of the exenterated orbit. PMID:24660959

Peter, Neena M; Laitt, Roger; Leatherbarrow, Brian

2014-06-01

449

Orbites coadjointes et variétés caractéristiques  

NASA Astrophysics Data System (ADS)

The purpose of the present work is to describe a dequantization procedure